diff --git a/session.go b/session.go
index 55133c745..5801e225c 100644
--- a/session.go
+++ b/session.go
@@ -1011,6 +1011,8 @@ type indexSpec struct {
 	DefaultLanguage  string  "default_language,omitempty"
 	LanguageOverride string  "language_override,omitempty"
 	TextIndexVersion int     "textIndexVersion,omitempty"
+
+	Collation *Collation "collation,omitempty"
 }
 
 type Index struct {
@@ -1049,6 +1051,54 @@ type Index struct {
 	// from the weighted sum of the frequency for each of the indexed fields in
 	// that document. The default field weight is 1.
 	Weights map[string]int
+
+	// Collation defines the collation to use for the index.
+	Collation *Collation
+}
+
+type Collation struct {
+
+	// Locale defines the collation locale.
+	Locale string `bson:"locale"`
+
+	// CaseLevel defines whether to turn case sensitivity on at strength 1 or 2.
+	CaseLevel bool `bson:"caseLevel,omitempty"`
+
+	// CaseFirst may be set to "upper" or "lower" to define whether
+	// to have uppercase or lowercase items first. Default is "off".
+	CaseFirst string `bson:"caseFirst,omitempty"`
+
+	// Strength defines the priority of comparison properties, as follows:
+	//
+	//   1 (primary)    - Strongest level, denote difference between base characters
+	//   2 (secondary)  - Accents in characters are considered secondary differences
+	//   3 (tertiary)   - Upper and lower case differences in characters are
+	//                    distinguished at the tertiary level
+	//   4 (quaternary) - When punctuation is ignored at level 1-3, an additional
+	//                    level can be used to distinguish words with and without
+	//                    punctuation. Should only be used if ignoring punctuation
+	//                    is required or when processing Japanese text.
+	//   5 (identical)  - When all other levels are equal, the identical level is
+	//                    used as a tiebreaker. The Unicode code point values of
+	//                    the NFD form of each string are compared at this level,
+	//                    just in case there is no difference at levels 1-4
+	//
+	// Strength defaults to 3.
+	Strength int `bson:"strength,omitempty"`
+
+	// NumericOrdering defines whether to order numbers based on numerical
+	// order and not collation order.
+	NumericOrdering bool `bson:"numericOrdering,omitempty"`
+
+	// Alternate controls whether spaces and punctuation are considered base characters.
+	// May be set to "non-ignorable" (spaces and punctuation considered base characters)
+	// or "shifted" (spaces and punctuation not considered base characters, and only
+	// distinguished at strength > 3). Defaults to "non-ignorable".
+	Alternate string `bson:"alternate,omitempty"`
+
+	// Backwards defines whether to have secondary differences considered in reverse order,
+	// as done in the French language.
+	Backwards bool `bson:"backwards,omitempty"`
 }
 
 // mgo.v3: Drop Minf and Maxf and transform Min and Max to floats.
@@ -1242,6 +1292,7 @@ func (c *Collection) EnsureIndex(index Index) error {
 		Weights:          keyInfo.weights,
 		DefaultLanguage:  index.DefaultLanguage,
 		LanguageOverride: index.LanguageOverride,
+		Collation:        index.Collation,
 	}
 
 	if spec.Min == 0 && spec.Max == 0 {
@@ -1456,6 +1507,7 @@ func indexFromSpec(spec indexSpec) Index {
 		DefaultLanguage:  spec.DefaultLanguage,
 		LanguageOverride: spec.LanguageOverride,
 		ExpireAfter:      time.Duration(spec.ExpireAfter) * time.Second,
+		Collation:        spec.Collation,
 	}
 	if float64(int(spec.Min)) == spec.Min && float64(int(spec.Max)) == spec.Max {
 		index.Min = int(spec.Min)
@@ -1584,7 +1636,7 @@ func (s *Session) Refresh() {
 }
 
 // SetMode changes the consistency mode for the session.
-// 
+//
 // The default mode is Strong.
 //
 // In the Strong consistency mode reads and writes will always be made to