diff --git a/CHANGELOG.md b/CHANGELOG.md
index 478a1b16cf5a..012c65d293f5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -60,6 +60,9 @@ longer panics if the store to load contains substores that we didn't explicitly
 * (simulation) [\#4824](https://github.com/cosmos/cosmos-sdk/issues/4824) PrintAllInvariants flag will print all failed invariants
 * (simulation) [\#4490](https://github.com/cosmos/cosmos-sdk/issues/4490) add `InitialBlockHeight` flag to resume a simulation from a given block
   * Support exporting the simulation stats to a given JSON file
+* (simulation) [\#4847](https://github.com/cosmos/cosmos-sdk/issues/4847) `SimApp` and simulation refactors
+  * Implement `SimulationManager` for executing modules' simulation functionalities in a modularized way
+  * Add `DecodeStore` to the `SimulationManager` for decoding each module's types
 * (simulation) [\#4893](https://github.com/cosmos/cosmos-sdk/issues/4893) Change SimApp keepers to be public and add getter functions for keys and codec
 * (store) [\#4792](https://github.com/cosmos/cosmos-sdk/issues/4792) panic on non-registered store
 * (types) [\#4821](https://github.com/cosmos/cosmos-sdk/issues/4821) types/errors package added with support for stacktraces. It is meant as a more feature-rich replacement for sdk.Errors in the mid-term.
diff --git a/client/cmd_test.go b/client/cmd_test.go
index ea71399a60bc..675cc296aeb4 100644
--- a/client/cmd_test.go
+++ b/client/cmd_test.go
@@ -1,4 +1,3 @@
-// nolint: misspell
 package client_test
 
 import (
@@ -38,10 +37,10 @@ func TestValidateCmd(t *testing.T) {
 		args    []string
 		wantErr bool
 	}{
-		{"misspelled command", []string{"comission"}, true},
+		{"misspelled command", []string{"comission"}, true}, // nolint: misspell
 		{"no command provided", []string{}, false},
-		{"help flag", []string{"comission", "--help"}, false},
-		{"shorthand help flag", []string{"comission", "-h"}, false},
+		{"help flag", []string{"comission", "--help"}, false},       // nolint: misspell
+		{"shorthand help flag", []string{"comission", "-h"}, false}, // nolint: misspell
 	}
 
 	for _, tt := range tests {
diff --git a/simapp/app.go b/simapp/app.go
index dcaa20c92586..b356cbef5b01 100644
--- a/simapp/app.go
+++ b/simapp/app.go
@@ -103,6 +103,9 @@ type SimApp struct {
 
 	// the module manager
 	mm *module.Manager
+
+	// simulation manager
+	sm *module.SimulationManager
 }
 
 // NewSimApp returns a reference to an initialized SimApp.
@@ -202,6 +205,9 @@ func NewSimApp(
 	app.mm.RegisterInvariants(&app.CrisisKeeper)
 	app.mm.RegisterRoutes(app.Router(), app.QueryRouter())
 
+	app.sm = module.NewSimulationManager(app.mm.Modules)
+	app.sm.RegisterStoreDecoders()
+
 	// initialize stores
 	app.MountKVStores(keys)
 	app.MountTransientStores(tkeys)
diff --git a/simapp/sim_test.go b/simapp/sim_test.go
index e130191ba25e..180e05b83a6f 100644
--- a/simapp/sim_test.go
+++ b/simapp/sim_test.go
@@ -20,20 +20,20 @@ import (
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	authsim "github.com/cosmos/cosmos-sdk/x/auth/simulation"
-	"github.com/cosmos/cosmos-sdk/x/bank"
+	authsimops "github.com/cosmos/cosmos-sdk/x/auth/simulation/operations"
+	banksimops "github.com/cosmos/cosmos-sdk/x/bank/simulation/operations"
 	distr "github.com/cosmos/cosmos-sdk/x/distribution"
-	distrsim "github.com/cosmos/cosmos-sdk/x/distribution/simulation"
+	distrsimops "github.com/cosmos/cosmos-sdk/x/distribution/simulation/operations"
 	"github.com/cosmos/cosmos-sdk/x/gov"
-	govsim "github.com/cosmos/cosmos-sdk/x/gov/simulation"
+	govsimops "github.com/cosmos/cosmos-sdk/x/gov/simulation/operations"
 	"github.com/cosmos/cosmos-sdk/x/mint"
 	"github.com/cosmos/cosmos-sdk/x/params"
-	paramsim "github.com/cosmos/cosmos-sdk/x/params/simulation"
+	paramsimops "github.com/cosmos/cosmos-sdk/x/params/simulation/operations"
 	"github.com/cosmos/cosmos-sdk/x/simulation"
 	"github.com/cosmos/cosmos-sdk/x/slashing"
-	slashingsim "github.com/cosmos/cosmos-sdk/x/slashing/simulation"
+	slashingsimops "github.com/cosmos/cosmos-sdk/x/slashing/simulation/operations"
 	"github.com/cosmos/cosmos-sdk/x/staking"
-	stakingsim "github.com/cosmos/cosmos-sdk/x/staking/simulation"
+	stakingsimops "github.com/cosmos/cosmos-sdk/x/staking/simulation/operations"
 	"github.com/cosmos/cosmos-sdk/x/supply"
 )
 
@@ -184,7 +184,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			authsim.SimulateDeductFee(app.AccountKeeper, app.SupplyKeeper),
+			authsimops.SimulateDeductFee(app.AccountKeeper, app.SupplyKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -195,7 +195,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			bank.SimulateMsgSend(app.AccountKeeper, app.BankKeeper),
+			banksimops.SimulateMsgSend(app.AccountKeeper, app.BankKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -206,7 +206,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			bank.SimulateSingleInputMsgMultiSend(app.AccountKeeper, app.BankKeeper),
+			banksimops.SimulateSingleInputMsgMultiSend(app.AccountKeeper, app.BankKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -217,7 +217,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			distrsim.SimulateMsgSetWithdrawAddress(app.AccountKeeper, app.DistrKeeper),
+			distrsimops.SimulateMsgSetWithdrawAddress(app.DistrKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -228,7 +228,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			distrsim.SimulateMsgWithdrawDelegatorReward(app.AccountKeeper, app.DistrKeeper),
+			distrsimops.SimulateMsgWithdrawDelegatorReward(app.DistrKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -239,7 +239,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			distrsim.SimulateMsgWithdrawValidatorCommission(app.AccountKeeper, app.DistrKeeper),
+			distrsimops.SimulateMsgWithdrawValidatorCommission(app.DistrKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -250,7 +250,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			govsim.SimulateSubmittingVotingAndSlashingForProposal(app.GovKeeper, govsim.SimulateTextProposalContent),
+			govsimops.SimulateSubmittingVotingAndSlashingForProposal(app.GovKeeper, govsimops.SimulateTextProposalContent),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -261,7 +261,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			govsim.SimulateSubmittingVotingAndSlashingForProposal(app.GovKeeper, distrsim.SimulateCommunityPoolSpendProposalContent(app.DistrKeeper)),
+			govsimops.SimulateSubmittingVotingAndSlashingForProposal(app.GovKeeper, distrsimops.SimulateCommunityPoolSpendProposalContent(app.DistrKeeper)),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -272,7 +272,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			govsim.SimulateSubmittingVotingAndSlashingForProposal(app.GovKeeper, paramsim.SimulateParamChangeProposalContent),
+			govsimops.SimulateSubmittingVotingAndSlashingForProposal(app.GovKeeper, paramsimops.SimulateParamChangeProposalContent),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -283,7 +283,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			govsim.SimulateMsgDeposit(app.GovKeeper),
+			govsimops.SimulateMsgDeposit(app.GovKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -294,7 +294,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			stakingsim.SimulateMsgCreateValidator(app.AccountKeeper, app.StakingKeeper),
+			stakingsimops.SimulateMsgCreateValidator(app.AccountKeeper, app.StakingKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -305,7 +305,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			stakingsim.SimulateMsgEditValidator(app.StakingKeeper),
+			stakingsimops.SimulateMsgEditValidator(app.StakingKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -316,7 +316,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			stakingsim.SimulateMsgDelegate(app.AccountKeeper, app.StakingKeeper),
+			stakingsimops.SimulateMsgDelegate(app.AccountKeeper, app.StakingKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -327,7 +327,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			stakingsim.SimulateMsgUndelegate(app.AccountKeeper, app.StakingKeeper),
+			stakingsimops.SimulateMsgUndelegate(app.AccountKeeper, app.StakingKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -338,7 +338,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			stakingsim.SimulateMsgBeginRedelegate(app.AccountKeeper, app.StakingKeeper),
+			stakingsimops.SimulateMsgBeginRedelegate(app.AccountKeeper, app.StakingKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -349,7 +349,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			slashingsim.SimulateMsgUnjail(app.SlashingKeeper),
+			slashingsimops.SimulateMsgUnjail(app.SlashingKeeper),
 		},
 	}
 }
@@ -597,11 +597,15 @@ func TestAppImportExport(t *testing.T) {
 		storeKeyA := storeKeysPrefix.A
 		storeKeyB := storeKeysPrefix.B
 		prefixes := storeKeysPrefix.Prefixes
+
 		storeA := ctxA.KVStore(storeKeyA)
 		storeB := ctxB.KVStore(storeKeyB)
-		failedKVs := sdk.DiffKVStores(storeA, storeB, prefixes)
-		fmt.Printf("Compared %d key/value pairs between %s and %s\n", len(failedKVs)/2, storeKeyA, storeKeyB)
-		require.Len(t, failedKVs, 0, GetSimulationLog(storeKeyA.Name(), app.cdc, newApp.cdc, failedKVs))
+
+		failedKVAs, failedKVBs := sdk.DiffKVStores(storeA, storeB, prefixes)
+		require.Equal(t, len(failedKVAs), len(failedKVBs), "unequal sets of key-values to compare")
+
+		fmt.Printf("Compared %d key/value pairs between %s and %s\n", len(failedKVAs), storeKeyA, storeKeyB)
+		require.Len(t, failedKVAs, 0, GetSimulationLog(storeKeyA.Name(), app.sm.StoreDecoders, app.cdc, failedKVAs, failedKVBs))
 	}
 
 }
diff --git a/simapp/utils.go b/simapp/utils.go
index 2bfa859e5cd6..90bc28176e9f 100644
--- a/simapp/utils.go
+++ b/simapp/utils.go
@@ -2,8 +2,6 @@
 package simapp
 
 import (
-	"bytes"
-	"encoding/binary"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -11,7 +9,6 @@ import (
 	"math/rand"
 	"time"
 
-	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/crypto/secp256k1"
 	cmn "github.com/tendermint/tendermint/libs/common"
 	"github.com/tendermint/tendermint/libs/log"
@@ -500,242 +497,21 @@ func GenStakingGenesisState(
 
 // GetSimulationLog unmarshals the KVPair's Value to the corresponding type based on the
 // each's module store key and the prefix bytes of the KVPair's key.
-func GetSimulationLog(storeName string, cdcA, cdcB *codec.Codec, kvs []cmn.KVPair) (log string) {
-	var kvA, kvB cmn.KVPair
-	for i := 0; i < len(kvs); i += 2 {
-		kvA = kvs[i]
-		kvB = kvs[i+1]
+func GetSimulationLog(storeName string, sdr sdk.StoreDecoderRegistry, cdc *codec.Codec, kvAs, kvBs []cmn.KVPair) (log string) {
+	for i := 0; i < len(kvAs); i++ {
 
-		if len(kvA.Value) == 0 && len(kvB.Value) == 0 {
+		if len(kvAs[i].Value) == 0 && len(kvBs[i].Value) == 0 {
 			// skip if the value doesn't have any bytes
 			continue
 		}
 
-		switch storeName {
-		case auth.StoreKey:
-			log += DecodeAccountStore(cdcA, cdcB, kvA, kvB)
-		case mint.StoreKey:
-			log += DecodeMintStore(cdcA, cdcB, kvA, kvB)
-		case staking.StoreKey:
-			log += DecodeStakingStore(cdcA, cdcB, kvA, kvB)
-		case slashing.StoreKey:
-			log += DecodeSlashingStore(cdcA, cdcB, kvA, kvB)
-		case gov.StoreKey:
-			log += DecodeGovStore(cdcA, cdcB, kvA, kvB)
-		case distribution.StoreKey:
-			log += DecodeDistributionStore(cdcA, cdcB, kvA, kvB)
-		case supply.StoreKey:
-			log += DecodeSupplyStore(cdcA, cdcB, kvA, kvB)
-		default:
-			log += fmt.Sprintf("store A %X => %X\nstore B %X => %X\n", kvA.Key, kvA.Value, kvB.Key, kvB.Value)
+		decoder, ok := sdr[storeName]
+		if ok {
+			log += decoder(cdc, kvAs[i], kvBs[i])
+		} else {
+			log += fmt.Sprintf("store A %X => %X\nstore B %X => %X\n", kvAs[i].Key, kvAs[i].Value, kvBs[i].Key, kvBs[i].Value)
 		}
 	}
 
 	return
 }
-
-// DecodeAccountStore unmarshals the KVPair's Value to the corresponding auth type
-func DecodeAccountStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key[:1], auth.AddressStoreKeyPrefix):
-		var accA, accB auth.Account
-		cdcA.MustUnmarshalBinaryBare(kvA.Value, &accA)
-		cdcB.MustUnmarshalBinaryBare(kvB.Value, &accB)
-		return fmt.Sprintf("%v\n%v", accA, accB)
-	case bytes.Equal(kvA.Key, auth.GlobalAccountNumberKey):
-		var globalAccNumberA, globalAccNumberB uint64
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &globalAccNumberA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &globalAccNumberB)
-		return fmt.Sprintf("GlobalAccNumberA: %d\nGlobalAccNumberB: %d", globalAccNumberA, globalAccNumberB)
-	default:
-		panic(fmt.Sprintf("invalid account key %X", kvA.Key))
-	}
-}
-
-// DecodeMintStore unmarshals the KVPair's Value to the corresponding mint type
-func DecodeMintStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key, mint.MinterKey):
-		var minterA, minterB mint.Minter
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &minterA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &minterB)
-		return fmt.Sprintf("%v\n%v", minterA, minterB)
-	default:
-		panic(fmt.Sprintf("invalid mint key %X", kvA.Key))
-	}
-}
-
-// DecodeDistributionStore unmarshals the KVPair's Value to the corresponding distribution type
-func DecodeDistributionStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key[:1], distribution.FeePoolKey):
-		var feePoolA, feePoolB distribution.FeePool
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &feePoolA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &feePoolB)
-		return fmt.Sprintf("%v\n%v", feePoolA, feePoolB)
-
-	case bytes.Equal(kvA.Key[:1], distribution.ProposerKey):
-		return fmt.Sprintf("%v\n%v", sdk.ConsAddress(kvA.Value), sdk.ConsAddress(kvB.Value))
-
-	case bytes.Equal(kvA.Key[:1], distribution.ValidatorOutstandingRewardsPrefix):
-		var rewardsA, rewardsB distribution.ValidatorOutstandingRewards
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &rewardsA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &rewardsB)
-		return fmt.Sprintf("%v\n%v", rewardsA, rewardsB)
-
-	case bytes.Equal(kvA.Key[:1], distribution.DelegatorWithdrawAddrPrefix):
-		return fmt.Sprintf("%v\n%v", sdk.AccAddress(kvA.Value), sdk.AccAddress(kvB.Value))
-
-	case bytes.Equal(kvA.Key[:1], distribution.DelegatorStartingInfoPrefix):
-		var infoA, infoB distribution.DelegatorStartingInfo
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &infoA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &infoB)
-		return fmt.Sprintf("%v\n%v", infoA, infoB)
-
-	case bytes.Equal(kvA.Key[:1], distribution.ValidatorHistoricalRewardsPrefix):
-		var rewardsA, rewardsB distribution.ValidatorHistoricalRewards
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &rewardsA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &rewardsB)
-		return fmt.Sprintf("%v\n%v", rewardsA, rewardsB)
-
-	case bytes.Equal(kvA.Key[:1], distribution.ValidatorCurrentRewardsPrefix):
-		var rewardsA, rewardsB distribution.ValidatorCurrentRewards
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &rewardsA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &rewardsB)
-		return fmt.Sprintf("%v\n%v", rewardsA, rewardsB)
-
-	case bytes.Equal(kvA.Key[:1], distribution.ValidatorAccumulatedCommissionPrefix):
-		var commissionA, commissionB distribution.ValidatorAccumulatedCommission
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &commissionA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &commissionB)
-		return fmt.Sprintf("%v\n%v", commissionA, commissionB)
-
-	case bytes.Equal(kvA.Key[:1], distribution.ValidatorSlashEventPrefix):
-		var eventA, eventB distribution.ValidatorSlashEvent
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &eventA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &eventB)
-		return fmt.Sprintf("%v\n%v", eventA, eventB)
-
-	default:
-		panic(fmt.Sprintf("invalid distribution key prefix %X", kvA.Key[:1]))
-	}
-}
-
-// DecodeStakingStore unmarshals the KVPair's Value to the corresponding staking type
-func DecodeStakingStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key[:1], staking.LastTotalPowerKey):
-		var powerA, powerB sdk.Int
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &powerA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &powerB)
-		return fmt.Sprintf("%v\n%v", powerA, powerB)
-
-	case bytes.Equal(kvA.Key[:1], staking.ValidatorsKey):
-		var validatorA, validatorB staking.Validator
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &validatorA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &validatorB)
-		return fmt.Sprintf("%v\n%v", validatorA, validatorB)
-
-	case bytes.Equal(kvA.Key[:1], staking.LastValidatorPowerKey),
-		bytes.Equal(kvA.Key[:1], staking.ValidatorsByConsAddrKey),
-		bytes.Equal(kvA.Key[:1], staking.ValidatorsByPowerIndexKey):
-		return fmt.Sprintf("%v\n%v", sdk.ValAddress(kvA.Value), sdk.ValAddress(kvB.Value))
-
-	case bytes.Equal(kvA.Key[:1], staking.DelegationKey):
-		var delegationA, delegationB staking.Delegation
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &delegationA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &delegationB)
-		return fmt.Sprintf("%v\n%v", delegationA, delegationB)
-
-	case bytes.Equal(kvA.Key[:1], staking.UnbondingDelegationKey),
-		bytes.Equal(kvA.Key[:1], staking.UnbondingDelegationByValIndexKey):
-		var ubdA, ubdB staking.UnbondingDelegation
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &ubdA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &ubdB)
-		return fmt.Sprintf("%v\n%v", ubdA, ubdB)
-
-	case bytes.Equal(kvA.Key[:1], staking.RedelegationKey),
-		bytes.Equal(kvA.Key[:1], staking.RedelegationByValSrcIndexKey):
-		var redA, redB staking.Redelegation
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &redA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &redB)
-		return fmt.Sprintf("%v\n%v", redA, redB)
-
-	default:
-		panic(fmt.Sprintf("invalid staking key prefix %X", kvA.Key[:1]))
-	}
-}
-
-// DecodeSlashingStore unmarshals the KVPair's Value to the corresponding slashing type
-func DecodeSlashingStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key[:1], slashing.ValidatorSigningInfoKey):
-		var infoA, infoB slashing.ValidatorSigningInfo
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &infoA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &infoB)
-		return fmt.Sprintf("%v\n%v", infoA, infoB)
-
-	case bytes.Equal(kvA.Key[:1], slashing.ValidatorMissedBlockBitArrayKey):
-		var missedA, missedB bool
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &missedA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &missedB)
-		return fmt.Sprintf("missedA: %v\nmissedB: %v", missedA, missedB)
-
-	case bytes.Equal(kvA.Key[:1], slashing.AddrPubkeyRelationKey):
-		var pubKeyA, pubKeyB crypto.PubKey
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &pubKeyA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &pubKeyB)
-		bechPKA := sdk.MustBech32ifyAccPub(pubKeyA)
-		bechPKB := sdk.MustBech32ifyAccPub(pubKeyB)
-		return fmt.Sprintf("PubKeyA: %s\nPubKeyB: %s", bechPKA, bechPKB)
-
-	default:
-		panic(fmt.Sprintf("invalid slashing key prefix %X", kvA.Key[:1]))
-	}
-}
-
-// DecodeGovStore unmarshals the KVPair's Value to the corresponding gov type
-func DecodeGovStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key[:1], gov.ProposalsKeyPrefix):
-		var proposalA, proposalB gov.Proposal
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &proposalA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &proposalB)
-		return fmt.Sprintf("%v\n%v", proposalA, proposalB)
-
-	case bytes.Equal(kvA.Key[:1], gov.ActiveProposalQueuePrefix),
-		bytes.Equal(kvA.Key[:1], gov.InactiveProposalQueuePrefix),
-		bytes.Equal(kvA.Key[:1], gov.ProposalIDKey):
-		proposalIDA := binary.LittleEndian.Uint64(kvA.Value)
-		proposalIDB := binary.LittleEndian.Uint64(kvB.Value)
-		return fmt.Sprintf("proposalIDA: %d\nProposalIDB: %d", proposalIDA, proposalIDB)
-
-	case bytes.Equal(kvA.Key[:1], gov.DepositsKeyPrefix):
-		var depositA, depositB gov.Deposit
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &depositA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &depositB)
-		return fmt.Sprintf("%v\n%v", depositA, depositB)
-
-	case bytes.Equal(kvA.Key[:1], gov.VotesKeyPrefix):
-		var voteA, voteB gov.Vote
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &voteA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &voteB)
-		return fmt.Sprintf("%v\n%v", voteA, voteB)
-
-	default:
-		panic(fmt.Sprintf("invalid governance key prefix %X", kvA.Key[:1]))
-	}
-}
-
-// DecodeSupplyStore unmarshals the KVPair's Value to the corresponding supply type
-func DecodeSupplyStore(cdcA, cdcB *codec.Codec, kvA, kvB cmn.KVPair) string {
-	switch {
-	case bytes.Equal(kvA.Key[:1], supply.SupplyKey):
-		var supplyA, supplyB supply.Supply
-		cdcA.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &supplyA)
-		cdcB.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &supplyB)
-		return fmt.Sprintf("%v\n%v", supplyB, supplyB)
-	default:
-		panic(fmt.Sprintf("invalid supply key %X", kvA.Key))
-	}
-}
diff --git a/simapp/utils_test.go b/simapp/utils_test.go
index ce51e686d460..d64ea8999dea 100644
--- a/simapp/utils_test.go
+++ b/simapp/utils_test.go
@@ -1,10 +1,7 @@
 package simapp
 
 import (
-	"encoding/binary"
 	"fmt"
-	"time"
-
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -15,13 +12,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/distribution"
-	distr "github.com/cosmos/cosmos-sdk/x/distribution"
-	"github.com/cosmos/cosmos-sdk/x/gov"
-	"github.com/cosmos/cosmos-sdk/x/mint"
-	"github.com/cosmos/cosmos-sdk/x/slashing"
-	"github.com/cosmos/cosmos-sdk/x/staking"
-	"github.com/cosmos/cosmos-sdk/x/supply"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
@@ -38,322 +28,40 @@ func makeTestCodec() (cdc *codec.Codec) {
 	sdk.RegisterCodec(cdc)
 	codec.RegisterCrypto(cdc)
 	auth.RegisterCodec(cdc)
-	distr.RegisterCodec(cdc)
-	gov.RegisterCodec(cdc)
-	staking.RegisterCodec(cdc)
-	supply.RegisterCodec(cdc)
 	return
 }
 
 func TestGetSimulationLog(t *testing.T) {
 	cdc := makeTestCodec()
 
-	tests := []struct {
-		store   string
-		kvPairs []cmn.KVPair
-	}{
-		{auth.StoreKey, []cmn.KVPair{
-			{Key: auth.AddressStoreKey(delAddr1), Value: cdc.MustMarshalBinaryBare(auth.BaseAccount{})},
-			{Key: auth.AddressStoreKey(delAddr1), Value: cdc.MustMarshalBinaryBare(auth.BaseAccount{})},
-		}},
-		{mint.StoreKey, []cmn.KVPair{
-			{Key: mint.MinterKey, Value: cdc.MustMarshalBinaryLengthPrefixed(mint.Minter{})},
-			{Key: mint.MinterKey, Value: cdc.MustMarshalBinaryLengthPrefixed(mint.Minter{})},
-		}},
-		{staking.StoreKey, []cmn.KVPair{
-			{Key: staking.LastValidatorPowerKey, Value: valAddr1.Bytes()},
-			{Key: staking.LastValidatorPowerKey, Value: valAddr1.Bytes()},
-		}},
-		{gov.StoreKey, []cmn.KVPair{
-			{Key: gov.VoteKey(1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(gov.Vote{})},
-			{Key: gov.VoteKey(1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(gov.Vote{})},
-		}},
-		{distribution.StoreKey, []cmn.KVPair{
-			{Key: distr.ProposerKey, Value: consAddr1.Bytes()},
-			{Key: distr.ProposerKey, Value: consAddr1.Bytes()},
-		}},
-		{slashing.StoreKey, []cmn.KVPair{
-			{Key: slashing.GetValidatorMissedBlockBitArrayKey(consAddr1, 6), Value: cdc.MustMarshalBinaryLengthPrefixed(true)},
-			{Key: slashing.GetValidatorMissedBlockBitArrayKey(consAddr1, 6), Value: cdc.MustMarshalBinaryLengthPrefixed(true)},
-		}},
-		{supply.StoreKey, []cmn.KVPair{
-			{Key: supply.SupplyKey, Value: cdc.MustMarshalBinaryLengthPrefixed(supply.NewSupply(sdk.Coins{}))},
-			{Key: supply.SupplyKey, Value: cdc.MustMarshalBinaryLengthPrefixed(supply.NewSupply(sdk.Coins{}))},
-		}},
-		{"Empty", []cmn.KVPair{{}, {}}},
-		{"OtherStore", []cmn.KVPair{
-			{Key: []byte("key"), Value: []byte("value")},
-			{Key: []byte("key"), Value: []byte("other_value")},
-		}},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.store, func(t *testing.T) {
-			require.NotPanics(t, func() { GetSimulationLog(tt.store, cdc, cdc, tt.kvPairs) }, tt.store)
-		})
-	}
-}
-
-func TestDecodeAccountStore(t *testing.T) {
-	cdc := makeTestCodec()
-	acc := auth.NewBaseAccountWithAddress(delAddr1)
-	globalAccNumber := uint64(10)
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: auth.AddressStoreKey(delAddr1), Value: cdc.MustMarshalBinaryBare(acc)},
-		cmn.KVPair{Key: auth.GlobalAccountNumberKey, Value: cdc.MustMarshalBinaryLengthPrefixed(globalAccNumber)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
-	tests := []struct {
-		name        string
-		expectedLog string
-	}{
-		{"Minter", fmt.Sprintf("%v\n%v", acc, acc)},
-		{"GlobalAccNumber", fmt.Sprintf("GlobalAccNumberA: %d\nGlobalAccNumberB: %d", globalAccNumber, globalAccNumber)},
-		{"other", ""},
-	}
-
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeAccountStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeAccountStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
-		})
-	}
-}
-
-func TestDecodeMintStore(t *testing.T) {
-	cdc := makeTestCodec()
-	minter := mint.NewMinter(sdk.OneDec(), sdk.NewDec(15))
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: mint.MinterKey, Value: cdc.MustMarshalBinaryLengthPrefixed(minter)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
-	tests := []struct {
-		name        string
-		expectedLog string
-	}{
-		{"Minter", fmt.Sprintf("%v\n%v", minter, minter)},
-		{"other", ""},
-	}
-
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeMintStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeMintStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
-		})
-	}
-}
-
-func TestDecodeDistributionStore(t *testing.T) {
-	cdc := makeTestCodec()
-
-	decCoins := sdk.DecCoins{sdk.NewDecCoinFromDec(sdk.DefaultBondDenom, sdk.OneDec())}
-	feePool := distr.InitialFeePool()
-	feePool.CommunityPool = decCoins
-	info := distr.NewDelegatorStartingInfo(2, sdk.OneDec(), 200)
-	outstanding := distr.ValidatorOutstandingRewards{decCoins[0]}
-	commission := distr.ValidatorAccumulatedCommission{decCoins[0]}
-	historicalRewards := distr.NewValidatorHistoricalRewards(decCoins, 100)
-	currentRewards := distr.NewValidatorCurrentRewards(decCoins, 5)
-	slashEvent := distr.NewValidatorSlashEvent(10, sdk.OneDec())
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: distr.FeePoolKey, Value: cdc.MustMarshalBinaryLengthPrefixed(feePool)},
-		cmn.KVPair{Key: distr.ProposerKey, Value: consAddr1.Bytes()},
-		cmn.KVPair{Key: distr.GetValidatorOutstandingRewardsKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(outstanding)},
-		cmn.KVPair{Key: distr.GetDelegatorWithdrawAddrKey(delAddr1), Value: delAddr1.Bytes()},
-		cmn.KVPair{Key: distr.GetDelegatorStartingInfoKey(valAddr1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(info)},
-		cmn.KVPair{Key: distr.GetValidatorHistoricalRewardsKey(valAddr1, 100), Value: cdc.MustMarshalBinaryLengthPrefixed(historicalRewards)},
-		cmn.KVPair{Key: distr.GetValidatorCurrentRewardsKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(currentRewards)},
-		cmn.KVPair{Key: distr.GetValidatorAccumulatedCommissionKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(commission)},
-		cmn.KVPair{Key: distr.GetValidatorSlashEventKeyPrefix(valAddr1, 13), Value: cdc.MustMarshalBinaryLengthPrefixed(slashEvent)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
-
-	tests := []struct {
-		name        string
-		expectedLog string
-	}{
-		{"FeePool", fmt.Sprintf("%v\n%v", feePool, feePool)},
-		{"Proposer", fmt.Sprintf("%v\n%v", consAddr1, consAddr1)},
-		{"ValidatorOutstandingRewards", fmt.Sprintf("%v\n%v", outstanding, outstanding)},
-		{"DelegatorWithdrawAddr", fmt.Sprintf("%v\n%v", delAddr1, delAddr1)},
-		{"DelegatorStartingInfo", fmt.Sprintf("%v\n%v", info, info)},
-		{"ValidatorHistoricalRewards", fmt.Sprintf("%v\n%v", historicalRewards, historicalRewards)},
-		{"ValidatorCurrentRewards", fmt.Sprintf("%v\n%v", currentRewards, currentRewards)},
-		{"ValidatorAccumulatedCommission", fmt.Sprintf("%v\n%v", commission, commission)},
-		{"ValidatorSlashEvent", fmt.Sprintf("%v\n%v", slashEvent, slashEvent)},
-		{"other", ""},
-	}
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeDistributionStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeDistributionStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
-		})
-	}
-}
-
-func TestDecodeStakingStore(t *testing.T) {
-	cdc := makeTestCodec()
-
-	bondTime := time.Now().UTC()
-
-	val := staking.NewValidator(valAddr1, delPk1, staking.NewDescription("test", "test", "test", "test", "test"))
-	del := staking.NewDelegation(delAddr1, valAddr1, sdk.OneDec())
-	ubd := staking.NewUnbondingDelegation(delAddr1, valAddr1, 15, bondTime, sdk.OneInt())
-	red := staking.NewRedelegation(delAddr1, valAddr1, valAddr1, 12, bondTime, sdk.OneInt(), sdk.OneDec())
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: staking.LastTotalPowerKey, Value: cdc.MustMarshalBinaryLengthPrefixed(sdk.OneInt())},
-		cmn.KVPair{Key: staking.GetValidatorKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(val)},
-		cmn.KVPair{Key: staking.LastValidatorPowerKey, Value: valAddr1.Bytes()},
-		cmn.KVPair{Key: staking.GetDelegationKey(delAddr1, valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(del)},
-		cmn.KVPair{Key: staking.GetUBDKey(delAddr1, valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(ubd)},
-		cmn.KVPair{Key: staking.GetREDKey(delAddr1, valAddr1, valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(red)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
-
-	tests := []struct {
-		name        string
-		expectedLog string
-	}{
-		{"LastTotalPower", fmt.Sprintf("%v\n%v", sdk.OneInt(), sdk.OneInt())},
-		{"Validator", fmt.Sprintf("%v\n%v", val, val)},
-		{"LastValidatorPower/ValidatorsByConsAddr/ValidatorsByPowerIndex", fmt.Sprintf("%v\n%v", valAddr1, valAddr1)},
-		{"Delegation", fmt.Sprintf("%v\n%v", del, del)},
-		{"UnbondingDelegation", fmt.Sprintf("%v\n%v", ubd, ubd)},
-		{"Redelegation", fmt.Sprintf("%v\n%v", red, red)},
-		{"other", ""},
-	}
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeStakingStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeStakingStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
-		})
-	}
-}
-
-func TestDecodeSlashingStore(t *testing.T) {
-	cdc := makeTestCodec()
-
-	info := slashing.NewValidatorSigningInfo(consAddr1, 0, 1, time.Now().UTC(), false, 0)
-	bechPK := sdk.MustBech32ifyAccPub(delPk1)
-	missed := true
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: slashing.GetValidatorSigningInfoKey(consAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(info)},
-		cmn.KVPair{Key: slashing.GetValidatorMissedBlockBitArrayKey(consAddr1, 6), Value: cdc.MustMarshalBinaryLengthPrefixed(missed)},
-		cmn.KVPair{Key: slashing.GetAddrPubkeyRelationKey(delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(delPk1)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
-
-	tests := []struct {
-		name        string
-		expectedLog string
-	}{
-		{"ValidatorSigningInfo", fmt.Sprintf("%v\n%v", info, info)},
-		{"ValidatorMissedBlockBitArray", fmt.Sprintf("missedA: %v\nmissedB: %v", missed, missed)},
-		{"AddrPubkeyRelation", fmt.Sprintf("PubKeyA: %s\nPubKeyB: %s", bechPK, bechPK)},
-		{"other", ""},
-	}
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeSlashingStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeSlashingStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
-		})
-	}
-}
-
-func TestDecodeGovStore(t *testing.T) {
-	cdc := makeTestCodec()
-
-	endTime := time.Now().UTC()
-
-	content := gov.ContentFromProposalType("test", "test", gov.ProposalTypeText)
-	proposal := gov.NewProposal(content, 1, endTime, endTime.Add(24*time.Hour))
-	proposalIDBz := make([]byte, 8)
-	binary.LittleEndian.PutUint64(proposalIDBz, 1)
-	deposit := gov.NewDeposit(1, delAddr1, sdk.NewCoins(sdk.NewCoin(sdk.DefaultBondDenom, sdk.OneInt())))
-	vote := gov.NewVote(1, delAddr1, gov.OptionYes)
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: gov.ProposalKey(1), Value: cdc.MustMarshalBinaryLengthPrefixed(proposal)},
-		cmn.KVPair{Key: gov.InactiveProposalQueueKey(1, endTime), Value: proposalIDBz},
-		cmn.KVPair{Key: gov.DepositKey(1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(deposit)},
-		cmn.KVPair{Key: gov.VoteKey(1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(vote)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
-
-	tests := []struct {
-		name        string
-		expectedLog string
-	}{
-		{"proposals", fmt.Sprintf("%v\n%v", proposal, proposal)},
-		{"proposal IDs", "proposalIDA: 1\nProposalIDB: 1"},
-		{"deposits", fmt.Sprintf("%v\n%v", deposit, deposit)},
-		{"votes", fmt.Sprintf("%v\n%v", vote, vote)},
-		{"other", ""},
-	}
-
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeGovStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeGovStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
-		})
-	}
-}
-
-func TestDecodeSupplyStore(t *testing.T) {
-	cdc := makeTestCodec()
-
-	totalSupply := supply.NewSupply(sdk.NewCoins(sdk.NewInt64Coin(sdk.DefaultBondDenom, 1000)))
-
-	kvPairs := cmn.KVPairs{
-		cmn.KVPair{Key: supply.SupplyKey, Value: cdc.MustMarshalBinaryLengthPrefixed(totalSupply)},
-		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
-	}
+	decoders := make(sdk.StoreDecoderRegistry)
+	decoders[auth.StoreKey] = func(cdc *codec.Codec, kvAs, kvBs cmn.KVPair) string { return "10" }
 
 	tests := []struct {
-		name        string
+		store       string
+		kvPairs     []cmn.KVPair
 		expectedLog string
 	}{
-		{"Supply", fmt.Sprintf("%v\n%v", totalSupply, totalSupply)},
-		{"other", ""},
+		{
+			"Empty",
+			[]cmn.KVPair{{}},
+			"",
+		},
+		{
+			auth.StoreKey,
+			[]cmn.KVPair{{Key: auth.GlobalAccountNumberKey, Value: cdc.MustMarshalBinaryLengthPrefixed(uint64(10))}},
+			"10",
+		},
+		{
+			"OtherStore",
+			[]cmn.KVPair{{Key: []byte("key"), Value: []byte("value")}},
+			fmt.Sprintf("store A %X => %X\nstore B %X => %X\n", []byte("key"), []byte("value"), []byte("key"), []byte("value")),
+		},
 	}
 
-	for i, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			switch i {
-			case len(tests) - 1:
-				require.Panics(t, func() { DecodeSupplyStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
-			default:
-				require.Equal(t, tt.expectedLog, DecodeSupplyStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
-			}
+	for _, tt := range tests {
+		t.Run(tt.store, func(t *testing.T) {
+			require.Equal(t, tt.expectedLog, GetSimulationLog(tt.store, decoders, cdc, tt.kvPairs, tt.kvPairs), tt.store)
 		})
 	}
 }
diff --git a/store/types/utils.go b/store/types/utils.go
index 39bc7da66500..9efcd02f1646 100644
--- a/store/types/utils.go
+++ b/store/types/utils.go
@@ -18,7 +18,7 @@ func KVStoreReversePrefixIterator(kvs KVStore, prefix []byte) Iterator {
 
 // DiffKVStores compares two KVstores and returns all the key/value pairs
 // that differ from one another. It also skips value comparison for a set of provided prefixes
-func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) (kvs []cmn.KVPair) {
+func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) (kvAs, kvBs []cmn.KVPair) {
 	iterA := a.Iterator(nil, nil)
 	iterB := b.Iterator(nil, nil)
 
@@ -36,7 +36,8 @@ func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) (kvs []cmn.KVPa
 			iterB.Next()
 		}
 		if !bytes.Equal(kvA.Key, kvB.Key) {
-			kvs = append(kvs, []cmn.KVPair{kvA, kvB}...)
+			kvAs = append(kvAs, kvA)
+			kvBs = append(kvBs, kvB)
 		}
 		compareValue := true
 		for _, prefix := range prefixesToSkip {
@@ -46,7 +47,8 @@ func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) (kvs []cmn.KVPa
 			}
 		}
 		if compareValue && !bytes.Equal(kvA.Value, kvB.Value) {
-			kvs = append(kvs, []cmn.KVPair{kvA, kvB}...)
+			kvAs = append(kvAs, kvA)
+			kvBs = append(kvBs, kvB)
 		}
 	}
 	return
diff --git a/types/module/module.go b/types/module/module.go
index f6083882d979..1501d6a394c0 100644
--- a/types/module/module.go
+++ b/types/module/module.go
@@ -3,6 +3,7 @@ Package module contains application module patterns and associated "manager" fun
 The module pattern has been broken down by:
  - independent module functionality (AppModuleBasic)
  - inter-dependent module genesis functionality (AppModuleGenesis)
+ - inter-dependent module simulation functionality (AppModuleSimulation)
  - inter-dependent module full functionality (AppModule)
 
 inter-dependent module functionality is module functionality which somehow
@@ -41,6 +42,7 @@ import (
 )
 
 //__________________________________________________________________________________________
+
 // AppModuleBasic is the standard form for basic non-dependant elements of an application module.
 type AppModuleBasic interface {
 	Name() string
@@ -56,9 +58,10 @@ type AppModuleBasic interface {
 	GetQueryCmd(*codec.Codec) *cobra.Command
 }
 
-// collections of AppModuleBasic
+// BasicManager is a collection of AppModuleBasic
 type BasicManager map[string]AppModuleBasic
 
+// NewBasicManager creates a new BasicManager object
 func NewBasicManager(modules ...AppModuleBasic) BasicManager {
 	moduleMap := make(map[string]AppModuleBasic)
 	for _, module := range modules {
@@ -67,14 +70,14 @@ func NewBasicManager(modules ...AppModuleBasic) BasicManager {
 	return moduleMap
 }
 
-// RegisterCodecs registers all module codecs
+// RegisterCodec registers all module codecs
 func (bm BasicManager) RegisterCodec(cdc *codec.Codec) {
 	for _, b := range bm {
 		b.RegisterCodec(cdc)
 	}
 }
 
-// Provided default genesis information for all modules
+// DefaultGenesis provides default genesis information for all modules
 func (bm BasicManager) DefaultGenesis() map[string]json.RawMessage {
 	genesis := make(map[string]json.RawMessage)
 	for _, b := range bm {
@@ -83,7 +86,7 @@ func (bm BasicManager) DefaultGenesis() map[string]json.RawMessage {
 	return genesis
 }
 
-// Provided default genesis information for all modules
+// ValidateGenesis performs genesis state validation for all modules
 func (bm BasicManager) ValidateGenesis(genesis map[string]json.RawMessage) error {
 	for _, b := range bm {
 		if err := b.ValidateGenesis(genesis[b.Name()]); err != nil {
@@ -93,14 +96,14 @@ func (bm BasicManager) ValidateGenesis(genesis map[string]json.RawMessage) error
 	return nil
 }
 
-// RegisterRestRoutes registers all module rest routes
+// RegisterRESTRoutes registers all module rest routes
 func (bm BasicManager) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	for _, b := range bm {
 		b.RegisterRESTRoutes(ctx, rtr)
 	}
 }
 
-// add all tx commands to the rootTxCmd
+// AddTxCommands adds all tx commands to the rootTxCmd
 func (bm BasicManager) AddTxCommands(rootTxCmd *cobra.Command, cdc *codec.Codec) {
 	for _, b := range bm {
 		if cmd := b.GetTxCmd(cdc); cmd != nil {
@@ -109,7 +112,7 @@ func (bm BasicManager) AddTxCommands(rootTxCmd *cobra.Command, cdc *codec.Codec)
 	}
 }
 
-// add all query commands to the rootQueryCmd
+// AddQueryCommands adds all query commands to the rootQueryCmd
 func (bm BasicManager) AddQueryCommands(rootQueryCmd *cobra.Command, cdc *codec.Codec) {
 	for _, b := range bm {
 		if cmd := b.GetQueryCmd(cdc); cmd != nil {
@@ -119,6 +122,7 @@ func (bm BasicManager) AddQueryCommands(rootQueryCmd *cobra.Command, cdc *codec.
 }
 
 //_________________________________________________________
+
 // AppModuleGenesis is the standard form for an application module genesis functions
 type AppModuleGenesis interface {
 	AppModuleBasic
@@ -126,9 +130,17 @@ type AppModuleGenesis interface {
 	ExportGenesis(sdk.Context) json.RawMessage
 }
 
+// AppModuleSimulation defines the standard functions that every module should expose
+// for the SDK blockchain simulator
+type AppModuleSimulation interface {
+	// register a func to decode the each module's defined types from their corresponding store key
+	RegisterStoreDecoder(sdk.StoreDecoderRegistry)
+}
+
 // AppModule is the standard form for an application module
 type AppModule interface {
 	AppModuleGenesis
+	AppModuleSimulation
 
 	// registers
 	RegisterInvariants(sdk.InvariantRegistry)
@@ -139,12 +151,14 @@ type AppModule interface {
 	QuerierRoute() string
 	NewQuerierHandler() sdk.Querier
 
+	// ABCI
 	BeginBlock(sdk.Context, abci.RequestBeginBlock)
 	EndBlock(sdk.Context, abci.RequestEndBlock) []abci.ValidatorUpdate
 }
 
 //___________________________
-// app module
+
+// GenesisOnlyAppModule is an AppModule that only has import/export functionality
 type GenesisOnlyAppModule struct {
 	AppModuleGenesis
 }
@@ -156,31 +170,35 @@ func NewGenesisOnlyAppModule(amg AppModuleGenesis) AppModule {
 	}
 }
 
-// register invariants
+// RegisterInvariants is a placeholder function register no invariants
 func (GenesisOnlyAppModule) RegisterInvariants(_ sdk.InvariantRegistry) {}
 
-// module message route ngame
+// RegisterStoreDecoder empty store decoder registry
+func (GenesisOnlyAppModule) RegisterStoreDecoder(_ sdk.StoreDecoderRegistry) {}
+
+// Route empty module message route
 func (GenesisOnlyAppModule) Route() string { return "" }
 
-// module handler
+// NewHandler returns an empty module handler
 func (GenesisOnlyAppModule) NewHandler() sdk.Handler { return nil }
 
-// module querier route ngame
+// QuerierRoute returns an empty module querier route
 func (GenesisOnlyAppModule) QuerierRoute() string { return "" }
 
-// module querier
+// NewQuerierHandler returns an empty module querier
 func (gam GenesisOnlyAppModule) NewQuerierHandler() sdk.Querier { return nil }
 
-// module begin-block
+// BeginBlock returns an empty module begin-block
 func (gam GenesisOnlyAppModule) BeginBlock(ctx sdk.Context, req abci.RequestBeginBlock) {}
 
-// module end-block
+// EndBlock returns an empty module end-block
 func (GenesisOnlyAppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
 
 //____________________________________________________________________________
-// module manager provides the high level utility for managing and executing
+
+// Manager defines a module manager that provides the high level utility for managing and executing
 // operations for a group of modules
 type Manager struct {
 	Modules            map[string]AppModule
@@ -190,7 +208,7 @@ type Manager struct {
 	OrderEndBlockers   []string
 }
 
-// NewModuleManager creates a new Manager object
+// NewManager creates a new Manager object
 func NewManager(modules ...AppModule) *Manager {
 
 	moduleMap := make(map[string]AppModule)
@@ -209,34 +227,34 @@ func NewManager(modules ...AppModule) *Manager {
 	}
 }
 
-// set the order of init genesis calls
+// SetOrderInitGenesis sets the order of init genesis calls
 func (m *Manager) SetOrderInitGenesis(moduleNames ...string) {
 	m.OrderInitGenesis = moduleNames
 }
 
-// set the order of export genesis calls
+// SetOrderExportGenesis sets the order of export genesis calls
 func (m *Manager) SetOrderExportGenesis(moduleNames ...string) {
 	m.OrderExportGenesis = moduleNames
 }
 
-// set the order of set begin-blocker calls
+// SetOrderBeginBlockers sets the order of set begin-blocker calls
 func (m *Manager) SetOrderBeginBlockers(moduleNames ...string) {
 	m.OrderBeginBlockers = moduleNames
 }
 
-// set the order of set end-blocker calls
+// SetOrderEndBlockers sets the order of set end-blocker calls
 func (m *Manager) SetOrderEndBlockers(moduleNames ...string) {
 	m.OrderEndBlockers = moduleNames
 }
 
-// register all module routes and module querier routes
+// RegisterInvariants registers all module routes and module querier routes
 func (m *Manager) RegisterInvariants(ir sdk.InvariantRegistry) {
 	for _, module := range m.Modules {
 		module.RegisterInvariants(ir)
 	}
 }
 
-// register all module routes and module querier routes
+// RegisterRoutes registers all module routes and module querier routes
 func (m *Manager) RegisterRoutes(router sdk.Router, queryRouter sdk.QueryRouter) {
 	for _, module := range m.Modules {
 		if module.Route() != "" {
@@ -248,7 +266,7 @@ func (m *Manager) RegisterRoutes(router sdk.Router, queryRouter sdk.QueryRouter)
 	}
 }
 
-// perform init genesis functionality for modules
+// InitGenesis performs init genesis functionality for modules
 func (m *Manager) InitGenesis(ctx sdk.Context, genesisData map[string]json.RawMessage) abci.ResponseInitChain {
 	var validatorUpdates []abci.ValidatorUpdate
 	for _, moduleName := range m.OrderInitGenesis {
@@ -271,7 +289,7 @@ func (m *Manager) InitGenesis(ctx sdk.Context, genesisData map[string]json.RawMe
 	}
 }
 
-// perform export genesis functionality for modules
+// ExportGenesis performs export genesis functionality for modules
 func (m *Manager) ExportGenesis(ctx sdk.Context) map[string]json.RawMessage {
 	genesisData := make(map[string]json.RawMessage)
 	for _, moduleName := range m.OrderExportGenesis {
@@ -320,6 +338,4 @@ func (m *Manager) EndBlock(ctx sdk.Context, req abci.RequestEndBlock) abci.Respo
 		ValidatorUpdates: validatorUpdates,
 		Events:           ctx.EventManager().ABCIEvents(),
 	}
-}
-
-// DONTCOVER
+}
\ No newline at end of file
diff --git a/types/module/simulation.go b/types/module/simulation.go
new file mode 100644
index 000000000000..c6901677dc2e
--- /dev/null
+++ b/types/module/simulation.go
@@ -0,0 +1,27 @@
+package module
+
+import (
+	sdk "github.com/cosmos/cosmos-sdk/types"
+)
+
+// SimulationManager defines a simulation manager that provides the high level utility
+// for managing and executing simulation functionalities for a group of modules
+type SimulationManager struct {
+	Modules       map[string]AppModule
+	StoreDecoders sdk.StoreDecoderRegistry
+}
+
+// NewSimulationManager creates a new SimulationManager object
+func NewSimulationManager(moduleMap map[string]AppModule) *SimulationManager {
+	return &SimulationManager{
+		Modules:       moduleMap,
+		StoreDecoders: make(sdk.StoreDecoderRegistry),
+	}
+}
+
+// RegisterStoreDecoders registers each of the modules' store decoders into a map
+func (sm *SimulationManager) RegisterStoreDecoders() {
+	for _, module := range sm.Modules {
+		module.RegisterStoreDecoder(sm.StoreDecoders)
+	}
+}
diff --git a/types/store.go b/types/store.go
index 1ebeb62aed21..a8772117e0bb 100644
--- a/types/store.go
+++ b/types/store.go
@@ -3,6 +3,7 @@ package types
 import (
 	cmn "github.com/tendermint/tendermint/libs/common"
 
+	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/store/types"
 )
 
@@ -24,6 +25,10 @@ type (
 	Iterator         = types.Iterator
 )
 
+// StoreDecoderRegistry defines each of the modules store decoders. Used for ImportExport
+// simulation.
+type StoreDecoderRegistry map[string]func(cdc *codec.Codec, kvA, kvB cmn.KVPair) string
+
 // Iterator over all the keys with a certain prefix in ascending order
 func KVStorePrefixIterator(kvs KVStore, prefix []byte) Iterator {
 	return types.KVStorePrefixIterator(kvs, prefix)
@@ -36,7 +41,7 @@ func KVStoreReversePrefixIterator(kvs KVStore, prefix []byte) Iterator {
 
 // DiffKVStores compares two KVstores and returns all the key/value pairs
 // that differ from one another. It also skips value comparison for a set of provided prefixes
-func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) []cmn.KVPair {
+func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) (kvAs, kvBs []cmn.KVPair) {
 	return types.DiffKVStores(a, b, prefixesToSkip)
 }
 
diff --git a/x/auth/module.go b/x/auth/module.go
index ef978e020082..cb45b4913dc0 100644
--- a/x/auth/module.go
+++ b/x/auth/module.go
@@ -13,33 +13,36 @@ import (
 	"github.com/cosmos/cosmos-sdk/types/module"
 	"github.com/cosmos/cosmos-sdk/x/auth/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/auth/client/rest"
+	"github.com/cosmos/cosmos-sdk/x/auth/simulation"
 	"github.com/cosmos/cosmos-sdk/x/auth/types"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the auth module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the auth module's name.
 func (AppModuleBasic) Name() string {
 	return types.ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the auth module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	types.RegisterCodec(cdc)
 }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the auth
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return types.ModuleCdc.MustMarshalJSON(types.DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the auth module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data types.GenesisState
 	err := types.ModuleCdc.UnmarshalJSON(bz, &data)
@@ -49,61 +52,76 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return types.ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the auth module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr, types.StoreKey)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns the root tx command for the auth module.
 func (AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetTxCmd(cdc)
 }
 
-// get the root query command of this module
+// GetQueryCmd returns the root query command for the auth module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(cdc)
 }
 
-//___________________________
-// app module object
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the auth module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for auth module's types
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the auth module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	accountKeeper AccountKeeper
 }
 
 // NewAppModule creates a new AppModule object
 func NewAppModule(accountKeeper AccountKeeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		accountKeeper:  accountKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		accountKeeper:       accountKeeper,
 	}
 }
 
-// module name
+// Name returns the auth module's name.
 func (AppModule) Name() string {
 	return types.ModuleName
 }
 
-// register invariants
+// RegisterInvariants performs a no-op.
 func (AppModule) RegisterInvariants(_ sdk.InvariantRegistry) {}
 
-// module message route name
+// Route returns the message routing key for the auth module.
 func (AppModule) Route() string { return "" }
 
-// module handler
+// NewHandler returns an sdk.Handler for the auth module.
 func (AppModule) NewHandler() sdk.Handler { return nil }
 
-// module querier route name
+// QuerierRoute returns the auth module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return types.QuerierRoute
 }
 
-// module querier
+// NewQuerierHandler returns the auth module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.accountKeeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the auth module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	types.ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -111,16 +129,18 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the auth
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.accountKeeper)
 	return types.ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock returns the begin blocker for the auth module.
 func (AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock) {}
 
-// module end-block
+// EndBlock returns the end blocker for the auth module. It returns no validator
+// updates.
 func (AppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
diff --git a/x/auth/simulation/decoder.go b/x/auth/simulation/decoder.go
new file mode 100644
index 000000000000..933421630bb9
--- /dev/null
+++ b/x/auth/simulation/decoder.go
@@ -0,0 +1,30 @@
+package simulation
+
+import (
+	"bytes"
+	"fmt"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/x/auth/exported"
+	"github.com/cosmos/cosmos-sdk/x/auth/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding auth type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key[:1], types.AddressStoreKeyPrefix):
+		var accA, accB exported.Account
+		cdc.MustUnmarshalBinaryBare(kvA.Value, &accA)
+		cdc.MustUnmarshalBinaryBare(kvB.Value, &accB)
+		return fmt.Sprintf("%v\n%v", accA, accB)
+	case bytes.Equal(kvA.Key, types.GlobalAccountNumberKey):
+		var globalAccNumberA, globalAccNumberB uint64
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &globalAccNumberA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &globalAccNumberB)
+		return fmt.Sprintf("GlobalAccNumberA: %d\nGlobalAccNumberB: %d", globalAccNumberA, globalAccNumberB)
+	default:
+		panic(fmt.Sprintf("invalid account key %X", kvA.Key))
+	}
+}
diff --git a/x/auth/simulation/decoder_test.go b/x/auth/simulation/decoder_test.go
new file mode 100644
index 000000000000..7b2cbe710a6a
--- /dev/null
+++ b/x/auth/simulation/decoder_test.go
@@ -0,0 +1,61 @@
+package simulation
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/auth/types"
+)
+
+var (
+	delPk1    = ed25519.GenPrivKey().PubKey()
+	delAddr1  = sdk.AccAddress(delPk1.Address())
+	valAddr1  = sdk.ValAddress(delPk1.Address())
+	consAddr1 = sdk.ConsAddress(delPk1.Address().Bytes())
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	codec.RegisterCrypto(cdc)
+	types.RegisterCodec(cdc)
+	return
+}
+
+func TestDecodeStore(t *testing.T) {
+	cdc := makeTestCodec()
+	acc := types.NewBaseAccountWithAddress(delAddr1)
+	globalAccNumber := uint64(10)
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: types.AddressStoreKey(delAddr1), Value: cdc.MustMarshalBinaryBare(acc)},
+		cmn.KVPair{Key: types.GlobalAccountNumberKey, Value: cdc.MustMarshalBinaryLengthPrefixed(globalAccNumber)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"Account", fmt.Sprintf("%v\n%v", acc, acc)},
+		{"GlobalAccNumber", fmt.Sprintf("GlobalAccNumberA: %d\nGlobalAccNumberB: %d", globalAccNumber, globalAccNumber)},
+		{"other", ""},
+	}
+
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}
diff --git a/x/auth/simulation/fake.go b/x/auth/simulation/operations/fake.go
similarity index 99%
rename from x/auth/simulation/fake.go
rename to x/auth/simulation/operations/fake.go
index 18e528f7bcb0..9a516785cb5d 100644
--- a/x/auth/simulation/fake.go
+++ b/x/auth/simulation/operations/fake.go
@@ -1,4 +1,4 @@
-package simulation
+package operations
 
 import (
 	"errors"
diff --git a/x/bank/module.go b/x/bank/module.go
index bd0a8d54dbc6..c2545036a758 100644
--- a/x/bank/module.go
+++ b/x/bank/module.go
@@ -19,25 +19,27 @@ import (
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the bank module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the bank module's name.
 func (AppModuleBasic) Name() string { return ModuleName }
 
-// register module codec
+// RegisterCodec registers the bank module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) { RegisterCodec(cdc) }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the bank
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the bank module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -47,23 +49,34 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the bank module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns the root tx command for the bank module.
 func (AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetTxCmd(cdc)
 }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the bank module.
 func (AppModuleBasic) GetQueryCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-//___________________________
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the bank module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder performs a no-op.
+func (AppModuleSimulation) RegisterStoreDecoder(_ sdk.StoreDecoderRegistry) {}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the bank module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper        Keeper
 	accountKeeper types.AccountKeeper
 }
@@ -71,35 +84,37 @@ type AppModule struct {
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper Keeper, accountKeeper types.AccountKeeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
-		accountKeeper:  accountKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
+		accountKeeper:       accountKeeper,
 	}
 }
 
-// module name
+// Name returns the bank module's name.
 func (AppModule) Name() string { return ModuleName }
 
-// register invariants
+// RegisterInvariants registers the bank module invariants.
 func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
 	keeper.RegisterInvariants(ir, am.accountKeeper)
 }
 
-// module message route name
+// Route returns the message routing key for the bank module.
 func (AppModule) Route() string { return RouterKey }
 
-// module handler
+// NewHandler returns an sdk.Handler for the bank module.
 func (am AppModule) NewHandler() sdk.Handler { return NewHandler(am.keeper) }
 
-// module querier route name
+// QuerierRoute returns the bank module's querier route name.
 func (AppModule) QuerierRoute() string { return RouterKey }
 
-// module querier
+// NewQuerierHandler returns the bank module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return keeper.NewQuerier(am.keeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the bank module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -107,16 +122,18 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the bank
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock performs a no-op.
 func (AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock) {}
 
-// module end-block
+// EndBlock returns the end blocker for the bank module. It returns no validator
+// updates.
 func (AppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
diff --git a/x/bank/simulation.go b/x/bank/simulation/operations/msgs.go
similarity index 94%
rename from x/bank/simulation.go
rename to x/bank/simulation/operations/msgs.go
index 85532502eaab..32ff0ad6eb01 100644
--- a/x/bank/simulation.go
+++ b/x/bank/simulation/operations/msgs.go
@@ -1,4 +1,4 @@
-package bank
+package operations
 
 import (
 	"fmt"
@@ -8,16 +8,16 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	sdk "github.com/cosmos/cosmos-sdk/types"
-	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/bank"
 	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 	"github.com/cosmos/cosmos-sdk/x/mock"
 	"github.com/cosmos/cosmos-sdk/x/simulation"
 )
 
-// SendTx tests and runs a single msg send where both
+// SimulateMsgSend tests and runs a single msg send where both
 // accounts already exist.
-func SimulateMsgSend(mapper types.AccountKeeper, bk keeper.Keeper) simulation.Operation {
-	handler := NewHandler(bk)
+func SimulateMsgSend(mapper types.AccountKeeper, bk bank.Keeper) simulation.Operation {
+	handler := bank.NewHandler(bk)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context, accs []simulation.Account) (
 		opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
 
@@ -108,10 +108,10 @@ func sendAndVerifyMsgSend(app *baseapp.BaseApp, mapper types.AccountKeeper, msg
 	return nil
 }
 
-// SingleInputSendMsg tests and runs a single msg multisend, with one input and one output, where both
+// SimulateSingleInputMsgMultiSend tests and runs a single msg multisend, with one input and one output, where both
 // accounts already exist.
-func SimulateSingleInputMsgMultiSend(mapper types.AccountKeeper, bk keeper.Keeper) simulation.Operation {
-	handler := NewHandler(bk)
+func SimulateSingleInputMsgMultiSend(mapper types.AccountKeeper, bk bank.Keeper) simulation.Operation {
+	handler := bank.NewHandler(bk)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context, accs []simulation.Account) (
 		opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
 
diff --git a/x/crisis/module.go b/x/crisis/module.go
index 456e5cc7b906..ec84c736d3c8 100644
--- a/x/crisis/module.go
+++ b/x/crisis/module.go
@@ -18,8 +18,9 @@ import (
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
 // AppModuleBasic defines the basic application module used by the crisis module.
@@ -61,9 +62,20 @@ func (AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 // GetQueryCmd returns no root query command for the crisis module.
 func (AppModuleBasic) GetQueryCmd(_ *codec.Codec) *cobra.Command { return nil }
 
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the crisis module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder performs a no-op.
+func (AppModuleSimulation) RegisterStoreDecoder(_ sdk.StoreDecoderRegistry) {}
+
+//____________________________________________________________________________
+
 // AppModule implements an application module for the crisis module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
 
 	// NOTE: We store a reference to the keeper here so that after a module
 	// manager is created, the invariants can be properly registered and
@@ -74,8 +86,9 @@ type AppModule struct {
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper *keeper.Keeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
 	}
 }
 
@@ -121,7 +134,7 @@ func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	return types.ModuleCdc.MustMarshalJSON(gs)
 }
 
-// BeginBlock returns the begin blocker for the crisis module.
+// BeginBlock performs a no-op.
 func (AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock) {}
 
 // EndBlock returns the end blocker for the crisis module. It returns no validator
diff --git a/x/distribution/module.go b/x/distribution/module.go
index 6fe513ad613e..c156e67aad49 100644
--- a/x/distribution/module.go
+++ b/x/distribution/module.go
@@ -14,33 +14,36 @@ import (
 	"github.com/cosmos/cosmos-sdk/types/module"
 	"github.com/cosmos/cosmos-sdk/x/distribution/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/distribution/client/rest"
+	"github.com/cosmos/cosmos-sdk/x/distribution/simulation"
 	"github.com/cosmos/cosmos-sdk/x/distribution/types"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the distribution module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the distribution module's name.
 func (AppModuleBasic) Name() string {
 	return ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the distribution module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	RegisterCodec(cdc)
 }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the distribution
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the distribution module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -50,24 +53,38 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the distribution module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr, StoreKey)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns the root tx command for the distribution module.
 func (AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetTxCmd(StoreKey, cdc)
 }
 
-// get the root query command of this module
+// GetQueryCmd returns the root query command for the distribution module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(StoreKey, cdc)
 }
 
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the distribution module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for distribution module's types
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the distribution module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper       Keeper
 	supplyKeeper types.SupplyKeeper
 }
@@ -75,43 +92,45 @@ type AppModule struct {
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper Keeper, supplyKeeper types.SupplyKeeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
-		supplyKeeper:   supplyKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
+		supplyKeeper:        supplyKeeper,
 	}
 }
 
-// module name
+// Name returns the distribution module's name.
 func (AppModule) Name() string {
 	return ModuleName
 }
 
-// register invariants
+// RegisterInvariants registers the distribution module invariants.
 func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
 	RegisterInvariants(ir, am.keeper)
 }
 
-// module message route name
+// Route returns the message routing key for the distribution module.
 func (AppModule) Route() string {
 	return RouterKey
 }
 
-// module handler
+// NewHandler returns an sdk.Handler for the distribution module.
 func (am AppModule) NewHandler() sdk.Handler {
 	return NewHandler(am.keeper)
 }
 
-// module querier route name
+// QuerierRoute returns the distribution module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return QuerierRoute
 }
 
-// module querier
+// NewQuerierHandler returns the distribution module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.keeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the distribution module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -119,18 +138,20 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the distribution
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock returns the begin blocker for the distribution module.
 func (am AppModule) BeginBlock(ctx sdk.Context, req abci.RequestBeginBlock) {
 	BeginBlocker(ctx, req, am.keeper)
 }
 
-// module end-block
+// EndBlock returns the end blocker for the distribution module. It returns no validator
+// updates.
 func (AppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
diff --git a/x/distribution/simulation/decoder.go b/x/distribution/simulation/decoder.go
new file mode 100644
index 000000000000..c1b8dce42821
--- /dev/null
+++ b/x/distribution/simulation/decoder.go
@@ -0,0 +1,70 @@
+package simulation
+
+import (
+	"bytes"
+	"fmt"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/distribution/keeper"
+	"github.com/cosmos/cosmos-sdk/x/distribution/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding distribution type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key[:1], keeper.FeePoolKey):
+		var feePoolA, feePoolB types.FeePool
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &feePoolA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &feePoolB)
+		return fmt.Sprintf("%v\n%v", feePoolA, feePoolB)
+
+	case bytes.Equal(kvA.Key[:1], keeper.ProposerKey):
+		return fmt.Sprintf("%v\n%v", sdk.ConsAddress(kvA.Value), sdk.ConsAddress(kvB.Value))
+
+	case bytes.Equal(kvA.Key[:1], keeper.ValidatorOutstandingRewardsPrefix):
+		var rewardsA, rewardsB types.ValidatorOutstandingRewards
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &rewardsA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &rewardsB)
+		return fmt.Sprintf("%v\n%v", rewardsA, rewardsB)
+
+	case bytes.Equal(kvA.Key[:1], keeper.DelegatorWithdrawAddrPrefix):
+		return fmt.Sprintf("%v\n%v", sdk.AccAddress(kvA.Value), sdk.AccAddress(kvB.Value))
+
+	case bytes.Equal(kvA.Key[:1], keeper.DelegatorStartingInfoPrefix):
+		var infoA, infoB types.DelegatorStartingInfo
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &infoA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &infoB)
+		return fmt.Sprintf("%v\n%v", infoA, infoB)
+
+	case bytes.Equal(kvA.Key[:1], keeper.ValidatorHistoricalRewardsPrefix):
+		var rewardsA, rewardsB types.ValidatorHistoricalRewards
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &rewardsA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &rewardsB)
+		return fmt.Sprintf("%v\n%v", rewardsA, rewardsB)
+
+	case bytes.Equal(kvA.Key[:1], keeper.ValidatorCurrentRewardsPrefix):
+		var rewardsA, rewardsB types.ValidatorCurrentRewards
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &rewardsA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &rewardsB)
+		return fmt.Sprintf("%v\n%v", rewardsA, rewardsB)
+
+	case bytes.Equal(kvA.Key[:1], keeper.ValidatorAccumulatedCommissionPrefix):
+		var commissionA, commissionB types.ValidatorAccumulatedCommission
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &commissionA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &commissionB)
+		return fmt.Sprintf("%v\n%v", commissionA, commissionB)
+
+	case bytes.Equal(kvA.Key[:1], keeper.ValidatorSlashEventPrefix):
+		var eventA, eventB types.ValidatorSlashEvent
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &eventA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &eventB)
+		return fmt.Sprintf("%v\n%v", eventA, eventB)
+
+	default:
+		panic(fmt.Sprintf("invalid distribution key prefix %X", kvA.Key[:1]))
+	}
+}
diff --git a/x/distribution/simulation/decoder_test.go b/x/distribution/simulation/decoder_test.go
new file mode 100644
index 000000000000..25d846e252d9
--- /dev/null
+++ b/x/distribution/simulation/decoder_test.go
@@ -0,0 +1,84 @@
+package simulation
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/distribution/keeper"
+	"github.com/cosmos/cosmos-sdk/x/distribution/types"
+)
+
+var (
+	delPk1    = ed25519.GenPrivKey().PubKey()
+	delAddr1  = sdk.AccAddress(delPk1.Address())
+	valAddr1  = sdk.ValAddress(delPk1.Address())
+	consAddr1 = sdk.ConsAddress(delPk1.Address().Bytes())
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	codec.RegisterCrypto(cdc)
+	types.RegisterCodec(cdc)
+	return
+}
+
+func TestDecodeDistributionStore(t *testing.T) {
+	cdc := makeTestCodec()
+
+	decCoins := sdk.DecCoins{sdk.NewDecCoinFromDec(sdk.DefaultBondDenom, sdk.OneDec())}
+	feePool := types.InitialFeePool()
+	feePool.CommunityPool = decCoins
+	info := types.NewDelegatorStartingInfo(2, sdk.OneDec(), 200)
+	outstanding := types.ValidatorOutstandingRewards{decCoins[0]}
+	commission := types.ValidatorAccumulatedCommission{decCoins[0]}
+	historicalRewards := types.NewValidatorHistoricalRewards(decCoins, 100)
+	currentRewards := types.NewValidatorCurrentRewards(decCoins, 5)
+	slashEvent := types.NewValidatorSlashEvent(10, sdk.OneDec())
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: keeper.FeePoolKey, Value: cdc.MustMarshalBinaryLengthPrefixed(feePool)},
+		cmn.KVPair{Key: keeper.ProposerKey, Value: consAddr1.Bytes()},
+		cmn.KVPair{Key: keeper.GetValidatorOutstandingRewardsKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(outstanding)},
+		cmn.KVPair{Key: keeper.GetDelegatorWithdrawAddrKey(delAddr1), Value: delAddr1.Bytes()},
+		cmn.KVPair{Key: keeper.GetDelegatorStartingInfoKey(valAddr1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(info)},
+		cmn.KVPair{Key: keeper.GetValidatorHistoricalRewardsKey(valAddr1, 100), Value: cdc.MustMarshalBinaryLengthPrefixed(historicalRewards)},
+		cmn.KVPair{Key: keeper.GetValidatorCurrentRewardsKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(currentRewards)},
+		cmn.KVPair{Key: keeper.GetValidatorAccumulatedCommissionKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(commission)},
+		cmn.KVPair{Key: keeper.GetValidatorSlashEventKeyPrefix(valAddr1, 13), Value: cdc.MustMarshalBinaryLengthPrefixed(slashEvent)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"FeePool", fmt.Sprintf("%v\n%v", feePool, feePool)},
+		{"Proposer", fmt.Sprintf("%v\n%v", consAddr1, consAddr1)},
+		{"ValidatorOutstandingRewards", fmt.Sprintf("%v\n%v", outstanding, outstanding)},
+		{"DelegatorWithdrawAddr", fmt.Sprintf("%v\n%v", delAddr1, delAddr1)},
+		{"DelegatorStartingInfo", fmt.Sprintf("%v\n%v", info, info)},
+		{"ValidatorHistoricalRewards", fmt.Sprintf("%v\n%v", historicalRewards, historicalRewards)},
+		{"ValidatorCurrentRewards", fmt.Sprintf("%v\n%v", currentRewards, currentRewards)},
+		{"ValidatorAccumulatedCommission", fmt.Sprintf("%v\n%v", commission, commission)},
+		{"ValidatorSlashEvent", fmt.Sprintf("%v\n%v", slashEvent, slashEvent)},
+		{"other", ""},
+	}
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}
diff --git a/x/distribution/simulation/msgs.go b/x/distribution/simulation/operations/msgs.go
similarity index 88%
rename from x/distribution/simulation/msgs.go
rename to x/distribution/simulation/operations/msgs.go
index ae002010c17a..6d30aac278c3 100644
--- a/x/distribution/simulation/msgs.go
+++ b/x/distribution/simulation/operations/msgs.go
@@ -1,4 +1,4 @@
-package simulation
+package operations
 
 import (
 	"fmt"
@@ -6,15 +6,14 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	sdk "github.com/cosmos/cosmos-sdk/types"
-	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/distribution"
 	"github.com/cosmos/cosmos-sdk/x/gov"
-	govsim "github.com/cosmos/cosmos-sdk/x/gov/simulation"
+	govsimops "github.com/cosmos/cosmos-sdk/x/gov/simulation/operations"
 	"github.com/cosmos/cosmos-sdk/x/simulation"
 )
 
 // SimulateMsgSetWithdrawAddress generates a MsgSetWithdrawAddress with random values.
-func SimulateMsgSetWithdrawAddress(m auth.AccountKeeper, k distribution.Keeper) simulation.Operation {
+func SimulateMsgSetWithdrawAddress(k distribution.Keeper) simulation.Operation {
 	handler := distribution.NewHandler(k)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context,
 		accs []simulation.Account) (opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
@@ -39,7 +38,7 @@ func SimulateMsgSetWithdrawAddress(m auth.AccountKeeper, k distribution.Keeper)
 }
 
 // SimulateMsgWithdrawDelegatorReward generates a MsgWithdrawDelegatorReward with random values.
-func SimulateMsgWithdrawDelegatorReward(m auth.AccountKeeper, k distribution.Keeper) simulation.Operation {
+func SimulateMsgWithdrawDelegatorReward(k distribution.Keeper) simulation.Operation {
 	handler := distribution.NewHandler(k)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context,
 		accs []simulation.Account) (opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
@@ -64,7 +63,7 @@ func SimulateMsgWithdrawDelegatorReward(m auth.AccountKeeper, k distribution.Kee
 }
 
 // SimulateMsgWithdrawValidatorCommission generates a MsgWithdrawValidatorCommission with random values.
-func SimulateMsgWithdrawValidatorCommission(m auth.AccountKeeper, k distribution.Keeper) simulation.Operation {
+func SimulateMsgWithdrawValidatorCommission(k distribution.Keeper) simulation.Operation {
 	handler := distribution.NewHandler(k)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context,
 		accs []simulation.Account) (opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
@@ -88,7 +87,7 @@ func SimulateMsgWithdrawValidatorCommission(m auth.AccountKeeper, k distribution
 }
 
 // SimulateCommunityPoolSpendProposalContent generates random community-pool-spend proposal content
-func SimulateCommunityPoolSpendProposalContent(k distribution.Keeper) govsim.ContentSimulator {
+func SimulateCommunityPoolSpendProposalContent(k distribution.Keeper) govsimops.ContentSimulator {
 	return func(r *rand.Rand, _ *baseapp.BaseApp, ctx sdk.Context, accs []simulation.Account) gov.Content {
 		recipientAcc := simulation.RandomAcc(r, accs)
 		coins := sdk.Coins{}
diff --git a/x/genaccounts/module.go b/x/genaccounts/module.go
index 90c01de8b15e..9a1f625aa96b 100644
--- a/x/genaccounts/module.go
+++ b/x/genaccounts/module.go
@@ -17,27 +17,29 @@ import (
 )
 
 var (
-	_ module.AppModuleGenesis = AppModule{}
-	_ module.AppModuleBasic   = AppModuleBasic{}
+	_ module.AppModuleGenesis    = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the genesis accounts module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the genesis accounts module's name.
 func (AppModuleBasic) Name() string {
 	return ModuleName
 }
 
-// register module codec
+// RegisterCodec performs a no-op.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {}
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the genesis accounts
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(GenesisState{})
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the genesis accounts module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -47,17 +49,18 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers no REST routes for the genesis accounts module.
 func (AppModuleBasic) RegisterRESTRoutes(_ context.CLIContext, _ *mux.Router) {}
 
-// get the root tx command of this module
+// GetTxCmd returns no root tx command for the genesis accounts module.
 func (AppModuleBasic) GetTxCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the genesis accounts module.
 func (AppModuleBasic) GetQueryCmd(_ *codec.Codec) *cobra.Command { return nil }
 
 // extra function from sdk.AppModuleBasic
-// iterate the genesis accounts and perform an operation at each of them
+
+// IterateGenesisAccounts iterates over the genesis accounts and perform an operation at each of them
 // - to used by other modules
 func (AppModuleBasic) IterateGenesisAccounts(cdc *codec.Codec, appGenesis map[string]json.RawMessage,
 	iterateFn func(exported.Account) (stop bool)) {
@@ -71,10 +74,21 @@ func (AppModuleBasic) IterateGenesisAccounts(cdc *codec.Codec, appGenesis map[st
 	}
 }
 
-//___________________________
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the genesis accounts module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder performs a no-op.
+func (AppModuleSimulation) RegisterStoreDecoder(_ sdk.StoreDecoderRegistry) {}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the genesis accounts module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	accountKeeper types.AccountKeeper
 }
 
@@ -82,12 +96,14 @@ type AppModule struct {
 func NewAppModule(accountKeeper types.AccountKeeper) module.AppModule {
 
 	return module.NewGenesisOnlyAppModule(AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		accountKeeper:  accountKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		accountKeeper:       accountKeeper,
 	})
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the genesis accounts module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -95,7 +111,8 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the genesis accounts
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.accountKeeper)
 	return ModuleCdc.MustMarshalJSON(gs)
diff --git a/x/genutil/module.go b/x/genutil/module.go
index f6051fccb549..63e0a93a4acc 100644
--- a/x/genutil/module.go
+++ b/x/genutil/module.go
@@ -16,27 +16,29 @@ import (
 )
 
 var (
-	_ module.AppModuleGenesis = AppModule{}
-	_ module.AppModuleBasic   = AppModuleBasic{}
+	_ module.AppModuleGenesis    = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the genutil module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the genutil module's name.
 func (AppModuleBasic) Name() string {
 	return ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the genutil module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {}
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the genutil
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(GenesisState{})
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the genutil module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -46,19 +48,30 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the genutil module.
 func (AppModuleBasic) RegisterRESTRoutes(_ context.CLIContext, _ *mux.Router) {}
 
-// get the root tx command of this module
+// GetTxCmd returns no root tx command for the genutil module.
 func (AppModuleBasic) GetTxCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the genutil module.
 func (AppModuleBasic) GetQueryCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-//___________________________
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the auth module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for genutil module's types
+func (AppModuleSimulation) RegisterStoreDecoder(_ sdk.StoreDecoderRegistry) {}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the genutil module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	accountKeeper types.AccountKeeper
 	stakingKeeper types.StakingKeeper
 	deliverTx     deliverTxfn
@@ -69,21 +82,24 @@ func NewAppModule(accountKeeper types.AccountKeeper,
 	stakingKeeper types.StakingKeeper, deliverTx deliverTxfn) module.AppModule {
 
 	return module.NewGenesisOnlyAppModule(AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		accountKeeper:  accountKeeper,
-		stakingKeeper:  stakingKeeper,
-		deliverTx:      deliverTx,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		accountKeeper:       accountKeeper,
+		stakingKeeper:       stakingKeeper,
+		deliverTx:           deliverTx,
 	})
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the genutil module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
 	return InitGenesis(ctx, ModuleCdc, am.stakingKeeper, am.deliverTx, genesisState)
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the genutil
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	return nil
 }
diff --git a/x/gov/module.go b/x/gov/module.go
index 16e304313032..81100e0ffae9 100644
--- a/x/gov/module.go
+++ b/x/gov/module.go
@@ -17,15 +17,17 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/gov/client"
 	"github.com/cosmos/cosmos-sdk/x/gov/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/gov/client/rest"
+	"github.com/cosmos/cosmos-sdk/x/gov/simulation"
 	"github.com/cosmos/cosmos-sdk/x/gov/types"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// AppModuleBasic - app module basics object
+// AppModuleBasic defines the basic application module used by the gov module.
 type AppModuleBasic struct {
 	proposalHandlers []client.ProposalHandler // proposal handlers which live in governance cli and rest
 }
@@ -37,24 +39,23 @@ func NewAppModuleBasic(proposalHandlers ...client.ProposalHandler) AppModuleBasi
 	}
 }
 
-var _ module.AppModuleBasic = AppModuleBasic{}
-
-// Name - module name
+// Name returns the gov module's name.
 func (AppModuleBasic) Name() string {
 	return types.ModuleName
 }
 
-// RegisterCodec -register module codec
+// RegisterCodec registers the gov module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	RegisterCodec(cdc)
 }
 
-// DefaultGenesis - default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the gov
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// ValidateGenesis - module validate genesis
+// ValidateGenesis performs genesis state validation for the gov module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -64,7 +65,7 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// RegisterRESTRoutes - register rest routes
+// RegisterRESTRoutes registers the REST routes for the gov module.
 func (a AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	var proposalRESTHandlers []rest.ProposalRESTHandler
 	for _, proposalHandler := range a.proposalHandlers {
@@ -74,7 +75,7 @@ func (a AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Rout
 	rest.RegisterRoutes(ctx, rtr, proposalRESTHandlers)
 }
 
-// GetTxCmd gets the root tx command of this module
+// GetTxCmd returns the root tx command for the gov module.
 func (a AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 
 	var proposalCLIHandlers []*cobra.Command
@@ -85,16 +86,28 @@ func (a AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetTxCmd(StoreKey, cdc, proposalCLIHandlers)
 }
 
-// GetQueryCmd gets the root query command of this module
+// GetQueryCmd returns the root query command for the gov module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(StoreKey, cdc)
 }
 
-//___________________________
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the gov module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder performs a no-op.
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
 
-// AppModule - app module object
+// AppModule implements an application module for the gov module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper       Keeper
 	supplyKeeper types.SupplyKeeper
 }
@@ -102,13 +115,14 @@ type AppModule struct {
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper Keeper, supplyKeeper types.SupplyKeeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
-		supplyKeeper:   supplyKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
+		supplyKeeper:        supplyKeeper,
 	}
 }
 
-// Name - module name
+// Name returns the gov module's name.
 func (AppModule) Name() string {
 	return ModuleName
 }
@@ -118,27 +132,28 @@ func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
 	RegisterInvariants(ir, am.keeper)
 }
 
-// Route - module message route name
+// Route returns the message routing key for the gov module.
 func (AppModule) Route() string {
 	return RouterKey
 }
 
-// NewHandler - module handler
+// NewHandler returns an sdk.Handler for the gov module.
 func (am AppModule) NewHandler() sdk.Handler {
 	return NewHandler(am.keeper)
 }
 
-// QuerierRoute - module querier route name
+// QuerierRoute returns the gov module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return QuerierRoute
 }
 
-// NewQuerierHandler - module querier
+// NewQuerierHandler returns no sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.keeper)
 }
 
-// InitGenesis - module init-genesis
+// InitGenesis performs genesis initialization for the gov module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -146,16 +161,18 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// ExportGenesis - module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the gov
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// BeginBlock - module begin-block
+// BeginBlock performs a no-op.
 func (AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock) {}
 
-// EndBlock - module end-block
+// EndBlock returns the end blocker for the gov module. It returns no validator
+// updates.
 func (am AppModule) EndBlock(ctx sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	EndBlocker(ctx, am.keeper)
 	return []abci.ValidatorUpdate{}
diff --git a/x/gov/simulation/decoder.go b/x/gov/simulation/decoder.go
new file mode 100644
index 000000000000..475721e8769e
--- /dev/null
+++ b/x/gov/simulation/decoder.go
@@ -0,0 +1,45 @@
+package simulation
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/x/gov/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding gov type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key[:1], types.ProposalsKeyPrefix):
+		var proposalA, proposalB types.Proposal
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &proposalA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &proposalB)
+		return fmt.Sprintf("%v\n%v", proposalA, proposalB)
+
+	case bytes.Equal(kvA.Key[:1], types.ActiveProposalQueuePrefix),
+		bytes.Equal(kvA.Key[:1], types.InactiveProposalQueuePrefix),
+		bytes.Equal(kvA.Key[:1], types.ProposalIDKey):
+		proposalIDA := binary.LittleEndian.Uint64(kvA.Value)
+		proposalIDB := binary.LittleEndian.Uint64(kvB.Value)
+		return fmt.Sprintf("proposalIDA: %d\nProposalIDB: %d", proposalIDA, proposalIDB)
+
+	case bytes.Equal(kvA.Key[:1], types.DepositsKeyPrefix):
+		var depositA, depositB types.Deposit
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &depositA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &depositB)
+		return fmt.Sprintf("%v\n%v", depositA, depositB)
+
+	case bytes.Equal(kvA.Key[:1], types.VotesKeyPrefix):
+		var voteA, voteB types.Vote
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &voteA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &voteB)
+		return fmt.Sprintf("%v\n%v", voteA, voteB)
+
+	default:
+		panic(fmt.Sprintf("invalid governance key prefix %X", kvA.Key[:1]))
+	}
+}
diff --git a/x/gov/simulation/decoder_test.go b/x/gov/simulation/decoder_test.go
new file mode 100644
index 000000000000..05d980023c2e
--- /dev/null
+++ b/x/gov/simulation/decoder_test.go
@@ -0,0 +1,75 @@
+package simulation
+
+import (
+	"encoding/binary"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/gov/types"
+)
+
+var (
+	delPk1    = ed25519.GenPrivKey().PubKey()
+	delAddr1  = sdk.AccAddress(delPk1.Address())
+	valAddr1  = sdk.ValAddress(delPk1.Address())
+	consAddr1 = sdk.ConsAddress(delPk1.Address().Bytes())
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	codec.RegisterCrypto(cdc)
+	types.RegisterCodec(cdc)
+	return
+}
+
+func TestDecodeStore(t *testing.T) {
+	cdc := makeTestCodec()
+
+	endTime := time.Now().UTC()
+
+	content := types.ContentFromProposalType("test", "test", types.ProposalTypeText)
+	proposal := types.NewProposal(content, 1, endTime, endTime.Add(24*time.Hour))
+	proposalIDBz := make([]byte, 8)
+	binary.LittleEndian.PutUint64(proposalIDBz, 1)
+	deposit := types.NewDeposit(1, delAddr1, sdk.NewCoins(sdk.NewCoin(sdk.DefaultBondDenom, sdk.OneInt())))
+	vote := types.NewVote(1, delAddr1, types.OptionYes)
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: types.ProposalKey(1), Value: cdc.MustMarshalBinaryLengthPrefixed(proposal)},
+		cmn.KVPair{Key: types.InactiveProposalQueueKey(1, endTime), Value: proposalIDBz},
+		cmn.KVPair{Key: types.DepositKey(1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(deposit)},
+		cmn.KVPair{Key: types.VoteKey(1, delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(vote)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"proposals", fmt.Sprintf("%v\n%v", proposal, proposal)},
+		{"proposal IDs", "proposalIDA: 1\nProposalIDB: 1"},
+		{"deposits", fmt.Sprintf("%v\n%v", deposit, deposit)},
+		{"votes", fmt.Sprintf("%v\n%v", vote, vote)},
+		{"other", ""},
+	}
+
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}
diff --git a/x/gov/simulation/msgs.go b/x/gov/simulation/operations/msgs.go
similarity index 99%
rename from x/gov/simulation/msgs.go
rename to x/gov/simulation/operations/msgs.go
index 0477e8273b88..f7dcba519de0 100644
--- a/x/gov/simulation/msgs.go
+++ b/x/gov/simulation/operations/msgs.go
@@ -1,4 +1,4 @@
-package simulation
+package operations
 
 import (
 	"fmt"
diff --git a/x/mint/module.go b/x/mint/module.go
index e8e07d94efd8..33b93ab54e81 100644
--- a/x/mint/module.go
+++ b/x/mint/module.go
@@ -14,32 +14,35 @@ import (
 	"github.com/cosmos/cosmos-sdk/types/module"
 	"github.com/cosmos/cosmos-sdk/x/mint/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/mint/client/rest"
+	"github.com/cosmos/cosmos-sdk/x/mint/simulation"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the mint module.
 type AppModuleBasic struct{}
 
 var _ module.AppModuleBasic = AppModuleBasic{}
 
-// module name
+// Name returns the mint module's name.
 func (AppModuleBasic) Name() string {
 	return ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the mint module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {}
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the mint
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the mint module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -49,59 +52,74 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the mint module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns no root tx command for the mint module.
 func (AppModuleBasic) GetTxCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-// get the root query command of this module
+// GetQueryCmd returns the root query command for the mint module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(cdc)
 }
 
-//___________________________
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the mint module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for mint module's types.
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the mint module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper Keeper
 }
 
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper Keeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
 	}
 }
 
-// module name
+// Name returns the mint module's name.
 func (AppModule) Name() string {
 	return ModuleName
 }
 
-// register invariants
+// RegisterInvariants registers the mint module invariants.
 func (am AppModule) RegisterInvariants(_ sdk.InvariantRegistry) {}
 
-// module message route name
+// Route returns the message routing key for the mint module.
 func (AppModule) Route() string { return "" }
 
-// module handler
+// NewHandler returns an sdk.Handler for the mint module.
 func (am AppModule) NewHandler() sdk.Handler { return nil }
 
-// module querier route name
+// QuerierRoute returns the mint module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return QuerierRoute
 }
 
-// module querier
+// NewQuerierHandler returns the mint module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.keeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the mint module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -109,18 +127,20 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the mint
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock returns the begin blocker for the mint module.
 func (am AppModule) BeginBlock(ctx sdk.Context, _ abci.RequestBeginBlock) {
 	BeginBlocker(ctx, am.keeper)
 }
 
-// module end-block
+// EndBlock returns the end blocker for the mint module. It returns no validator
+// updates.
 func (AppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
diff --git a/x/mint/simulation/decoder.go b/x/mint/simulation/decoder.go
new file mode 100644
index 000000000000..0f1ab1960989
--- /dev/null
+++ b/x/mint/simulation/decoder.go
@@ -0,0 +1,24 @@
+package simulation
+
+import (
+	"bytes"
+	"fmt"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/x/mint/internal/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding mint type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key, types.MinterKey):
+		var minterA, minterB types.Minter
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &minterA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &minterB)
+		return fmt.Sprintf("%v\n%v", minterA, minterB)
+	default:
+		panic(fmt.Sprintf("invalid mint key %X", kvA.Key))
+	}
+}
diff --git a/x/mint/simulation/decoder_test.go b/x/mint/simulation/decoder_test.go
new file mode 100644
index 000000000000..b6501baa7f06
--- /dev/null
+++ b/x/mint/simulation/decoder_test.go
@@ -0,0 +1,48 @@
+package simulation
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/mint/internal/types"
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	return
+}
+
+func TestDecodeStore(t *testing.T) {
+	cdc := makeTestCodec()
+	minter := types.NewMinter(sdk.OneDec(), sdk.NewDec(15))
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: types.MinterKey, Value: cdc.MustMarshalBinaryLengthPrefixed(minter)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"Minter", fmt.Sprintf("%v\n%v", minter, minter)},
+		{"other", ""},
+	}
+
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}
diff --git a/x/params/module.go b/x/params/module.go
index e339d954990c..38b93bd5f00c 100644
--- a/x/params/module.go
+++ b/x/params/module.go
@@ -16,32 +16,31 @@ var (
 	_ module.AppModuleBasic = AppModuleBasic{}
 )
 
-const moduleName = "params"
-
-// app module basics object
+// AppModuleBasic defines the basic application module used by the params module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the params module's name.
 func (AppModuleBasic) Name() string {
-	return moduleName
+	return ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the params module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	types.RegisterCodec(cdc)
 }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the params
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage { return nil }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the params module.
 func (AppModuleBasic) ValidateGenesis(_ json.RawMessage) error { return nil }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the params module.
 func (AppModuleBasic) RegisterRESTRoutes(_ context.CLIContext, _ *mux.Router) {}
 
-// get the root tx command of this module
+// GetTxCmd returns no root tx command for the params module.
 func (AppModuleBasic) GetTxCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the params module.
 func (AppModuleBasic) GetQueryCmd(_ *codec.Codec) *cobra.Command { return nil }
diff --git a/x/params/simulation/msgs.go b/x/params/simulation/operations/msgs.go
similarity index 99%
rename from x/params/simulation/msgs.go
rename to x/params/simulation/operations/msgs.go
index db7669ae09ed..b6b869dc6f23 100644
--- a/x/params/simulation/msgs.go
+++ b/x/params/simulation/operations/msgs.go
@@ -1,4 +1,4 @@
-package simulation
+package operations
 
 import (
 	"encoding/json"
diff --git a/x/slashing/module.go b/x/slashing/module.go
index e3ee17fc2c7e..986915a11531 100644
--- a/x/slashing/module.go
+++ b/x/slashing/module.go
@@ -15,34 +15,37 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/slashing/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/slashing/client/rest"
 	"github.com/cosmos/cosmos-sdk/x/slashing/internal/types"
+	"github.com/cosmos/cosmos-sdk/x/slashing/simulation"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the slashing module.
 type AppModuleBasic struct{}
 
 var _ module.AppModuleBasic = AppModuleBasic{}
 
-// module name
+// Name returns the slashing module's name.
 func (AppModuleBasic) Name() string {
 	return types.ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the slashing module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	RegisterCodec(cdc)
 }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the slashing
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the slashing module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -52,25 +55,38 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the slashing module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns the root tx command for the slashing module.
 func (AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetTxCmd(cdc)
 }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the slashing module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(StoreKey, cdc)
 }
 
-//___________________________
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the slashing module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for slashing module's types
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the slashing module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper        Keeper
 	stakingKeeper types.StakingKeeper
 }
@@ -78,41 +94,43 @@ type AppModule struct {
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper Keeper, stakingKeeper types.StakingKeeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
-		stakingKeeper:  stakingKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
+		stakingKeeper:       stakingKeeper,
 	}
 }
 
-// module name
+// Name returns the slashing module's name.
 func (AppModule) Name() string {
 	return ModuleName
 }
 
-// register invariants
+// RegisterInvariants registers the slashing module invariants.
 func (am AppModule) RegisterInvariants(_ sdk.InvariantRegistry) {}
 
-// module message route name
+// Route returns the message routing key for the slashing module.
 func (AppModule) Route() string {
 	return RouterKey
 }
 
-// module handler
+// NewHandler returns an sdk.Handler for the slashing module.
 func (am AppModule) NewHandler() sdk.Handler {
 	return NewHandler(am.keeper)
 }
 
-// module querier route name
+// QuerierRoute returns the slashing module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return QuerierRoute
 }
 
-// module querier
+// NewQuerierHandler returns the slashing module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.keeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the slashing module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -120,18 +138,20 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the slashing
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock returns the begin blocker for the slashing module.
 func (am AppModule) BeginBlock(ctx sdk.Context, req abci.RequestBeginBlock) {
 	BeginBlocker(ctx, req, am.keeper)
 }
 
-// module end-block
+// EndBlock returns the end blocker for the slashing module. It returns no validator
+// updates.
 func (AppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
diff --git a/x/slashing/simulation/decoder.go b/x/slashing/simulation/decoder.go
new file mode 100644
index 000000000000..99af7c0b722b
--- /dev/null
+++ b/x/slashing/simulation/decoder.go
@@ -0,0 +1,41 @@
+package simulation
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/tendermint/tendermint/crypto"
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/slashing/internal/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding slashing type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key[:1], types.ValidatorSigningInfoKey):
+		var infoA, infoB types.ValidatorSigningInfo
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &infoA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &infoB)
+		return fmt.Sprintf("%v\n%v", infoA, infoB)
+
+	case bytes.Equal(kvA.Key[:1], types.ValidatorMissedBlockBitArrayKey):
+		var missedA, missedB bool
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &missedA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &missedB)
+		return fmt.Sprintf("missedA: %v\nmissedB: %v", missedA, missedB)
+
+	case bytes.Equal(kvA.Key[:1], types.AddrPubkeyRelationKey):
+		var pubKeyA, pubKeyB crypto.PubKey
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &pubKeyA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &pubKeyB)
+		bechPKA := sdk.MustBech32ifyAccPub(pubKeyA)
+		bechPKB := sdk.MustBech32ifyAccPub(pubKeyB)
+		return fmt.Sprintf("PubKeyA: %s\nPubKeyB: %s", bechPKA, bechPKB)
+
+	default:
+		panic(fmt.Sprintf("invalid slashing key prefix %X", kvA.Key[:1]))
+	}
+}
diff --git a/x/slashing/simulation/decoder_test.go b/x/slashing/simulation/decoder_test.go
new file mode 100644
index 000000000000..1c8f8f93c542
--- /dev/null
+++ b/x/slashing/simulation/decoder_test.go
@@ -0,0 +1,66 @@
+package simulation
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/slashing/internal/types"
+)
+
+var (
+	delPk1    = ed25519.GenPrivKey().PubKey()
+	delAddr1  = sdk.AccAddress(delPk1.Address())
+	valAddr1  = sdk.ValAddress(delPk1.Address())
+	consAddr1 = sdk.ConsAddress(delPk1.Address().Bytes())
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	codec.RegisterCrypto(cdc)
+	types.RegisterCodec(cdc)
+	return
+}
+
+func TestDecodeStore(t *testing.T) {
+	cdc := makeTestCodec()
+
+	info := types.NewValidatorSigningInfo(consAddr1, 0, 1, time.Now().UTC(), false, 0)
+	bechPK := sdk.MustBech32ifyAccPub(delPk1)
+	missed := true
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: types.GetValidatorSigningInfoKey(consAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(info)},
+		cmn.KVPair{Key: types.GetValidatorMissedBlockBitArrayKey(consAddr1, 6), Value: cdc.MustMarshalBinaryLengthPrefixed(missed)},
+		cmn.KVPair{Key: types.GetAddrPubkeyRelationKey(delAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(delPk1)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"ValidatorSigningInfo", fmt.Sprintf("%v\n%v", info, info)},
+		{"ValidatorMissedBlockBitArray", fmt.Sprintf("missedA: %v\nmissedB: %v", missed, missed)},
+		{"AddrPubkeyRelation", fmt.Sprintf("PubKeyA: %s\nPubKeyB: %s", bechPK, bechPK)},
+		{"other", ""},
+	}
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}
diff --git a/x/slashing/simulation/msgs.go b/x/slashing/simulation/operations/msgs.go
similarity index 98%
rename from x/slashing/simulation/msgs.go
rename to x/slashing/simulation/operations/msgs.go
index 01acf4a81980..5772101b16b2 100644
--- a/x/slashing/simulation/msgs.go
+++ b/x/slashing/simulation/operations/msgs.go
@@ -1,4 +1,4 @@
-package simulation
+package operations
 
 import (
 	"fmt"
diff --git a/x/staking/module.go b/x/staking/module.go
index 8dcb26c66ec6..4bfd0c70aab5 100644
--- a/x/staking/module.go
+++ b/x/staking/module.go
@@ -18,35 +18,38 @@ import (
 	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	"github.com/cosmos/cosmos-sdk/x/staking/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/staking/client/rest"
+	"github.com/cosmos/cosmos-sdk/x/staking/simulation"
 	"github.com/cosmos/cosmos-sdk/x/staking/types"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the staking module.
 type AppModuleBasic struct{}
 
 var _ module.AppModuleBasic = AppModuleBasic{}
 
-// module name
+// Name returns the staking module's name.
 func (AppModuleBasic) Name() string {
 	return ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the staking module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	RegisterCodec(cdc)
 }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the staking
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the staking module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -56,17 +59,17 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the staking module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns the root tx command for the staking module.
 func (AppModuleBasic) GetTxCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetTxCmd(StoreKey, cdc)
 }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the staking module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(StoreKey, cdc)
 }
@@ -92,9 +95,23 @@ func (AppModuleBasic) BuildCreateValidatorMsg(cliCtx context.CLIContext,
 	return cli.BuildCreateValidatorMsg(cliCtx, txBldr)
 }
 
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the staking module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for staking module's types
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the staking module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper       Keeper
 	distrKeeper  types.DistributionKeeper
 	accKeeper    types.AccountKeeper
@@ -106,61 +123,65 @@ func NewAppModule(keeper Keeper, distrKeeper types.DistributionKeeper, accKeeper
 	supplyKeeper types.SupplyKeeper) AppModule {
 
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
-		distrKeeper:    distrKeeper,
-		accKeeper:      accKeeper,
-		supplyKeeper:   supplyKeeper,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
+		distrKeeper:         distrKeeper,
+		accKeeper:           accKeeper,
+		supplyKeeper:        supplyKeeper,
 	}
 }
 
-// module name
+// Name returns the staking module's name.
 func (AppModule) Name() string {
 	return ModuleName
 }
 
-// register invariants
+// RegisterInvariants registers the staking module invariants.
 func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
 	RegisterInvariants(ir, am.keeper)
 }
 
-// module message route name
+// Route returns the message routing key for the staking module.
 func (AppModule) Route() string {
 	return RouterKey
 }
 
-// module handler
+// NewHandler returns an sdk.Handler for the staking module.
 func (am AppModule) NewHandler() sdk.Handler {
 	return NewHandler(am.keeper)
 }
 
-// module querier route name
+// QuerierRoute returns the staking module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return QuerierRoute
 }
 
-// module querier
+// NewQuerierHandler returns the staking module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.keeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the staking module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
 	return InitGenesis(ctx, am.keeper, am.accKeeper, am.supplyKeeper, genesisState)
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the staking
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock returns the begin blocker for the staking module.
 func (AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock) {}
 
-// module end-block
+// EndBlock returns the end blocker for the staking module. It returns no validator
+// updates.
 func (am AppModule) EndBlock(ctx sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return EndBlocker(ctx, am.keeper)
 }
diff --git a/x/staking/simulation/decoder.go b/x/staking/simulation/decoder.go
new file mode 100644
index 000000000000..45aba449f807
--- /dev/null
+++ b/x/staking/simulation/decoder.go
@@ -0,0 +1,57 @@
+package simulation
+
+import (
+	"bytes"
+	"fmt"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/staking/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding staking type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key[:1], types.LastTotalPowerKey):
+		var powerA, powerB sdk.Int
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &powerA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &powerB)
+		return fmt.Sprintf("%v\n%v", powerA, powerB)
+
+	case bytes.Equal(kvA.Key[:1], types.ValidatorsKey):
+		var validatorA, validatorB types.Validator
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &validatorA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &validatorB)
+		return fmt.Sprintf("%v\n%v", validatorA, validatorB)
+
+	case bytes.Equal(kvA.Key[:1], types.LastValidatorPowerKey),
+		bytes.Equal(kvA.Key[:1], types.ValidatorsByConsAddrKey),
+		bytes.Equal(kvA.Key[:1], types.ValidatorsByPowerIndexKey):
+		return fmt.Sprintf("%v\n%v", sdk.ValAddress(kvA.Value), sdk.ValAddress(kvB.Value))
+
+	case bytes.Equal(kvA.Key[:1], types.DelegationKey):
+		var delegationA, delegationB types.Delegation
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &delegationA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &delegationB)
+		return fmt.Sprintf("%v\n%v", delegationA, delegationB)
+
+	case bytes.Equal(kvA.Key[:1], types.UnbondingDelegationKey),
+		bytes.Equal(kvA.Key[:1], types.UnbondingDelegationByValIndexKey):
+		var ubdA, ubdB types.UnbondingDelegation
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &ubdA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &ubdB)
+		return fmt.Sprintf("%v\n%v", ubdA, ubdB)
+
+	case bytes.Equal(kvA.Key[:1], types.RedelegationKey),
+		bytes.Equal(kvA.Key[:1], types.RedelegationByValSrcIndexKey):
+		var redA, redB types.Redelegation
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &redA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &redB)
+		return fmt.Sprintf("%v\n%v", redA, redB)
+
+	default:
+		panic(fmt.Sprintf("invalid staking key prefix %X", kvA.Key[:1]))
+	}
+}
diff --git a/x/staking/simulation/decoder_test.go b/x/staking/simulation/decoder_test.go
new file mode 100644
index 000000000000..19950c97aad4
--- /dev/null
+++ b/x/staking/simulation/decoder_test.go
@@ -0,0 +1,75 @@
+package simulation
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/staking/types"
+)
+
+var (
+	delPk1    = ed25519.GenPrivKey().PubKey()
+	delAddr1  = sdk.AccAddress(delPk1.Address())
+	valAddr1  = sdk.ValAddress(delPk1.Address())
+	consAddr1 = sdk.ConsAddress(delPk1.Address().Bytes())
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	codec.RegisterCrypto(cdc)
+	types.RegisterCodec(cdc)
+	return
+}
+
+func TestDecodeStore(t *testing.T) {
+	cdc := makeTestCodec()
+
+	bondTime := time.Now().UTC()
+
+	val := types.NewValidator(valAddr1, delPk1, types.NewDescription("test", "test", "test", "test", "test"))
+	del := types.NewDelegation(delAddr1, valAddr1, sdk.OneDec())
+	ubd := types.NewUnbondingDelegation(delAddr1, valAddr1, 15, bondTime, sdk.OneInt())
+	red := types.NewRedelegation(delAddr1, valAddr1, valAddr1, 12, bondTime, sdk.OneInt(), sdk.OneDec())
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: types.LastTotalPowerKey, Value: cdc.MustMarshalBinaryLengthPrefixed(sdk.OneInt())},
+		cmn.KVPair{Key: types.GetValidatorKey(valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(val)},
+		cmn.KVPair{Key: types.LastValidatorPowerKey, Value: valAddr1.Bytes()},
+		cmn.KVPair{Key: types.GetDelegationKey(delAddr1, valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(del)},
+		cmn.KVPair{Key: types.GetUBDKey(delAddr1, valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(ubd)},
+		cmn.KVPair{Key: types.GetREDKey(delAddr1, valAddr1, valAddr1), Value: cdc.MustMarshalBinaryLengthPrefixed(red)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"LastTotalPower", fmt.Sprintf("%v\n%v", sdk.OneInt(), sdk.OneInt())},
+		{"Validator", fmt.Sprintf("%v\n%v", val, val)},
+		{"LastValidatorPower/ValidatorsByConsAddr/ValidatorsByPowerIndex", fmt.Sprintf("%v\n%v", valAddr1, valAddr1)},
+		{"Delegation", fmt.Sprintf("%v\n%v", del, del)},
+		{"UnbondingDelegation", fmt.Sprintf("%v\n%v", ubd, ubd)},
+		{"Redelegation", fmt.Sprintf("%v\n%v", red, red)},
+		{"other", ""},
+	}
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}
diff --git a/x/staking/simulation/msgs.go b/x/staking/simulation/operations/msgs.go
similarity index 99%
rename from x/staking/simulation/msgs.go
rename to x/staking/simulation/operations/msgs.go
index f36a5e6d9802..caf6dd09c0bc 100644
--- a/x/staking/simulation/msgs.go
+++ b/x/staking/simulation/operations/msgs.go
@@ -1,4 +1,4 @@
-package simulation
+package operations
 
 import (
 	"fmt"
diff --git a/x/supply/module.go b/x/supply/module.go
index 3a987e2fa14d..5607b4d3207d 100644
--- a/x/supply/module.go
+++ b/x/supply/module.go
@@ -15,32 +15,35 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/supply/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/supply/client/rest"
 	"github.com/cosmos/cosmos-sdk/x/supply/internal/types"
+	"github.com/cosmos/cosmos-sdk/x/supply/simulation"
 )
 
 var (
-	_ module.AppModule      = AppModule{}
-	_ module.AppModuleBasic = AppModuleBasic{}
+	_ module.AppModule           = AppModule{}
+	_ module.AppModuleBasic      = AppModuleBasic{}
+	_ module.AppModuleSimulation = AppModuleSimulation{}
 )
 
-// app module basics object
+// AppModuleBasic defines the basic application module used by the supply module.
 type AppModuleBasic struct{}
 
-// module name
+// Name returns the supply module's name.
 func (AppModuleBasic) Name() string {
 	return ModuleName
 }
 
-// register module codec
+// RegisterCodec registers the supply module's types for the given codec.
 func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
 	RegisterCodec(cdc)
 }
 
-// default genesis state
+// DefaultGenesis returns default genesis state as raw bytes for the supply
+// module.
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
 	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
-// module validate genesis
+// ValidateGenesis performs genesis state validation for the supply module.
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
 	err := ModuleCdc.UnmarshalJSON(bz, &data)
@@ -50,22 +53,36 @@ func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	return ValidateGenesis(data)
 }
 
-// register rest routes
+// RegisterRESTRoutes registers the REST routes for the supply module.
 func (AppModuleBasic) RegisterRESTRoutes(ctx context.CLIContext, rtr *mux.Router) {
 	rest.RegisterRoutes(ctx, rtr)
 }
 
-// get the root tx command of this module
+// GetTxCmd returns the root tx command for the supply module.
 func (AppModuleBasic) GetTxCmd(_ *codec.Codec) *cobra.Command { return nil }
 
-// get the root query command of this module
+// GetQueryCmd returns no root query command for the supply module.
 func (AppModuleBasic) GetQueryCmd(cdc *codec.Codec) *cobra.Command {
 	return cli.GetQueryCmd(cdc)
 }
 
-// app module
+//____________________________________________________________________________
+
+// AppModuleSimulation defines the module simulation functions used by the supply module.
+type AppModuleSimulation struct{}
+
+// RegisterStoreDecoder registers a decoder for supply module's types
+func (AppModuleSimulation) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+	sdr[StoreKey] = simulation.DecodeStore
+}
+
+//____________________________________________________________________________
+
+// AppModule implements an application module for the supply module.
 type AppModule struct {
 	AppModuleBasic
+	AppModuleSimulation
+
 	keeper Keeper
 	ak     types.AccountKeeper
 }
@@ -73,41 +90,43 @@ type AppModule struct {
 // NewAppModule creates a new AppModule object
 func NewAppModule(keeper Keeper, ak types.AccountKeeper) AppModule {
 	return AppModule{
-		AppModuleBasic: AppModuleBasic{},
-		keeper:         keeper,
-		ak:             ak,
+		AppModuleBasic:      AppModuleBasic{},
+		AppModuleSimulation: AppModuleSimulation{},
+		keeper:              keeper,
+		ak:                  ak,
 	}
 }
 
-// module name
+// Name returns the supply module's name.
 func (AppModule) Name() string {
 	return ModuleName
 }
 
-// register invariants
+// RegisterInvariants registers the supply module invariants.
 func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
 	RegisterInvariants(ir, am.keeper)
 }
 
-// module message route name
+// Route returns the message routing key for the supply module.
 func (AppModule) Route() string {
 	return RouterKey
 }
 
-// module handler
+// NewHandler returns an sdk.Handler for the supply module.
 func (am AppModule) NewHandler() sdk.Handler { return nil }
 
-// module querier route name
+// QuerierRoute returns the supply module's querier route name.
 func (AppModule) QuerierRoute() string {
 	return QuerierRoute
 }
 
-// module querier
+// NewQuerierHandler returns the supply module sdk.Querier.
 func (am AppModule) NewQuerierHandler() sdk.Querier {
 	return NewQuerier(am.keeper)
 }
 
-// module init-genesis
+// InitGenesis performs genesis initialization for the supply module. It returns
+// no validator updates.
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
 	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
@@ -115,16 +134,18 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 	return []abci.ValidatorUpdate{}
 }
 
-// module export genesis
+// ExportGenesis returns the exported genesis state as raw bytes for the supply
+// module.
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
 	return ModuleCdc.MustMarshalJSON(gs)
 }
 
-// module begin-block
+// BeginBlock returns the begin blocker for the supply module.
 func (am AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock) {}
 
-// module end-block
+// EndBlock returns the end blocker for the supply module. It returns no validator
+// updates.
 func (AppModule) EndBlock(_ sdk.Context, _ abci.RequestEndBlock) []abci.ValidatorUpdate {
 	return []abci.ValidatorUpdate{}
 }
diff --git a/x/supply/simulation/decoder.go b/x/supply/simulation/decoder.go
new file mode 100644
index 000000000000..7e22f33a5478
--- /dev/null
+++ b/x/supply/simulation/decoder.go
@@ -0,0 +1,25 @@
+package simulation
+
+import (
+	"bytes"
+	"fmt"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/x/supply/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/supply/internal/types"
+)
+
+// DecodeStore unmarshals the KVPair's Value to the corresponding supply type
+func DecodeStore(cdc *codec.Codec, kvA, kvB cmn.KVPair) string {
+	switch {
+	case bytes.Equal(kvA.Key[:1], keeper.SupplyKey):
+		var supplyA, supplyB types.Supply
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvA.Value, &supplyA)
+		cdc.MustUnmarshalBinaryLengthPrefixed(kvB.Value, &supplyB)
+		return fmt.Sprintf("%v\n%v", supplyB, supplyB)
+	default:
+		panic(fmt.Sprintf("invalid supply key %X", kvA.Key))
+	}
+}
diff --git a/x/supply/simulation/decoder_test.go b/x/supply/simulation/decoder_test.go
new file mode 100644
index 000000000000..329b3e752747
--- /dev/null
+++ b/x/supply/simulation/decoder_test.go
@@ -0,0 +1,52 @@
+package simulation
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/supply/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/supply/internal/types"
+)
+
+func makeTestCodec() (cdc *codec.Codec) {
+	cdc = codec.New()
+	sdk.RegisterCodec(cdc)
+	codec.RegisterCrypto(cdc)
+	types.RegisterCodec(cdc)
+	return
+}
+func TestDecodeStore(t *testing.T) {
+	cdc := makeTestCodec()
+
+	totalSupply := types.NewSupply(sdk.NewCoins(sdk.NewInt64Coin(sdk.DefaultBondDenom, 1000)))
+
+	kvPairs := cmn.KVPairs{
+		cmn.KVPair{Key: keeper.SupplyKey, Value: cdc.MustMarshalBinaryLengthPrefixed(totalSupply)},
+		cmn.KVPair{Key: []byte{0x99}, Value: []byte{0x99}},
+	}
+
+	tests := []struct {
+		name        string
+		expectedLog string
+	}{
+		{"Supply", fmt.Sprintf("%v\n%v", totalSupply, totalSupply)},
+		{"other", ""},
+	}
+
+	for i, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch i {
+			case len(tests) - 1:
+				require.Panics(t, func() { DecodeStore(cdc, kvPairs[i], kvPairs[i]) }, tt.name)
+			default:
+				require.Equal(t, tt.expectedLog, DecodeStore(cdc, kvPairs[i], kvPairs[i]), tt.name)
+			}
+		})
+	}
+}