diff --git a/README.md b/README.md
index f45cbde..0cc9513 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,24 @@ appropriate helm command based on which action it is included within: `install`,
 
 ### Install or Upgrade
 
-```
+```shell
 porter mixin install helm
 ```
 
+### Configure mixin repositories
+
+```yaml
+- helm:
+    repositories:
+      stable:
+        url: "https://kubernetes-charts.storage.googleapis.com"
+        cafile: "path/to/cafile"
+        certfile: "path/to/certfile"
+        keyfile: "path/to/keyfile"
+        username: "username"
+        password: "password"
+```
+
 ### Mixin Syntax
 
 Install
diff --git a/pkg/helm/build.go b/pkg/helm/build.go
index 0b57158..538c6a8 100644
--- a/pkg/helm/build.go
+++ b/pkg/helm/build.go
@@ -2,6 +2,10 @@ package helm
 
 import (
 	"fmt"
+	"strings"
+
+	"get.porter.sh/porter/pkg/exec/builder"
+	yaml "gopkg.in/yaml.v2"
 )
 
 // These values may be referenced elsewhere (init.go), hence consts
@@ -29,8 +33,86 @@ const getKubectl string = `RUN apt-get update && \
  mv kubectl /usr/local/bin && \
  chmod a+x /usr/local/bin/kubectl`
 
+// BuildInput represents stdin passed to the mixin for the build command.
+type BuildInput struct {
+	Config MixinConfig
+}
+
+// MixinConfig represents configuration that can be set on the helm mixin in porter.yaml
+// mixins:
+// - helm:
+//	  repositories:
+//	    stable:
+//		  url: "https://kubernetes-charts.storage.googleapis.com"
+//		  cafile: "path/to/cafile"
+//		  certfile: "path/to/certfile"
+//		  keyfile: "path/to/keyfile"
+//		  username: "username"
+//		  password: "password"
+type MixinConfig struct {
+	Repositories map[string]Repository
+}
+
+type Repository struct {
+	URL      string `yaml:"url,omitempty"`
+	Cafile   string `yaml:"cafile,omitempty"`
+	Certfile string `yaml:"certfile,omitempty"`
+	Keyfile  string `yaml:"keyfile,omitempty"`
+	Username string `yaml:"username,omitempty"`
+	Password string `yaml:"password,omitempty"`
+}
+
 func (m *Mixin) Build() error {
+
+	// Create new Builder.
+	var input BuildInput
+	err := builder.LoadAction(m.Context, "", func(contents []byte) (interface{}, error) {
+		err := yaml.Unmarshal(contents, &input)
+		return &input, err
+	})
+	if err != nil {
+		return err
+	}
+
+	// Define helm
 	fmt.Fprintf(m.Out, getHelm, helmDownloadURL)
+
+	// Define kubectl
 	fmt.Fprintf(m.Out, getKubectl, kubeVersion)
+
+	// Go through repositories
+	for name, repo := range input.Config.Repositories {
+
+		commandValue, err := GetAddRepositoryCommand(name, repo.URL, repo.Cafile, repo.Certfile, repo.Keyfile, repo.Username, repo.Password)
+		if err != nil && m.Debug {
+			fmt.Fprintf(m.Err, "DEBUG: addition of repository failed: %s\n", err.Error())
+		} else {
+			fmt.Fprintf(m.Out, strings.Join(commandValue, " "))
+		}
+	}
+
 	return nil
 }
+
+func GetAddRepositoryCommand(name, url, cafile, certfile, keyfile, username, password string) (commandValue []string, err error) {
+
+	var commandBuilder []string
+
+	if url == "" {
+		return commandBuilder, fmt.Errorf("repository url must be supplied")
+	}
+
+	commandBuilder = append(commandBuilder, "\nRUN", "helm", "repo", "add", name, url)
+
+	if certfile != "" && keyfile != "" {
+		commandBuilder = append(commandBuilder, "--cert-file", certfile, "--key-file", keyfile)
+	}
+	if cafile != "" {
+		commandBuilder = append(commandBuilder, "--ca-file", cafile)
+	}
+	if username != "" && password != "" {
+		commandBuilder = append(commandBuilder, "--username", username, "--password", password)
+	}
+
+	return commandBuilder, nil
+}
diff --git a/pkg/helm/build_test.go b/pkg/helm/build_test.go
index 64e2ceb..dff5c81 100644
--- a/pkg/helm/build_test.go
+++ b/pkg/helm/build_test.go
@@ -1,6 +1,8 @@
 package helm
 
 import (
+	"bytes"
+	"io/ioutil"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -13,7 +15,7 @@ func TestMixin_Build(t *testing.T) {
 	err := m.Build()
 	require.NoError(t, err)
 
-	wantOutput := `RUN apt-get update && \
+	buildOutput := `RUN apt-get update && \
  apt-get install -y curl && \
  curl -o helm.tgz https://get.helm.sh/helm-v2.15.2-linux-amd64.tar.gz && \
  tar -xzf helm.tgz && \
@@ -26,6 +28,34 @@ RUN apt-get update && \
  mv kubectl /usr/local/bin && \
  chmod a+x /usr/local/bin/kubectl`
 
-	gotOutput := m.TestContext.GetOutput()
-	assert.Equal(t, wantOutput, gotOutput)
+	t.Run("build with a valid config", func(t *testing.T) {
+		b, err := ioutil.ReadFile("testdata/build-input-with-valid-config.yaml")
+		require.NoError(t, err)
+
+		m := NewTestMixin(t)
+		m.Debug = false
+		m.In = bytes.NewReader(b)
+
+		err = m.Build()
+		require.NoError(t, err, "build failed")
+
+		wantOutput := buildOutput + "\nRUN helm repo add stable kubernetes-charts --username username --password password"
+
+		gotOutput := m.TestContext.GetOutput()
+		assert.Equal(t, wantOutput, gotOutput)
+	})
+
+	t.Run("build with invalid config", func(t *testing.T) {
+		b, err := ioutil.ReadFile("testdata/build-input-with-invalid-config.yaml")
+		require.NoError(t, err)
+
+		m := NewTestMixin(t)
+		m.Debug = false
+		m.In = bytes.NewReader(b)
+
+		err = m.Build()
+		require.NoError(t, err, "build failed")
+		gotOutput := m.TestContext.GetOutput()
+		assert.Equal(t, buildOutput, gotOutput)
+	})
 }
diff --git a/pkg/helm/testdata/build-input-with-invalid-config.yaml b/pkg/helm/testdata/build-input-with-invalid-config.yaml
new file mode 100644
index 0000000..d86f09b
--- /dev/null
+++ b/pkg/helm/testdata/build-input-with-invalid-config.yaml
@@ -0,0 +1,9 @@
+config:
+  repositories:
+    stable:
+install:
+  - helm:
+      description: "Install MySQL"
+      name: porter-ci-mysql
+      chart: stable/mysql
+      version: 0.10.2
diff --git a/pkg/helm/testdata/build-input-with-valid-config.yaml b/pkg/helm/testdata/build-input-with-valid-config.yaml
new file mode 100644
index 0000000..a9734f0
--- /dev/null
+++ b/pkg/helm/testdata/build-input-with-valid-config.yaml
@@ -0,0 +1,12 @@
+config:
+  repositories:
+    stable:
+      url: "kubernetes-charts"
+      username: "username"
+      password: "password"
+install:
+  - helm:
+      description: "Install MySQL"
+      name: porter-ci-mysql
+      chart: stable/mysql
+      version: 0.10.2