diff --git a/modules/@angular/common/src/forms/directives/ng_control_name.ts b/modules/@angular/common/src/forms/directives/ng_control_name.ts
index 93fa3f6058..19d2908734 100644
--- a/modules/@angular/common/src/forms/directives/ng_control_name.ts
+++ b/modules/@angular/common/src/forms/directives/ng_control_name.ts
@@ -1,7 +1,7 @@
 import {
   OnChanges,
   OnDestroy,
-  SimpleChange,
+  SimpleChanges,
   Directive,
   forwardRef,
   Host,
@@ -114,7 +114,7 @@ export class NgControlName extends NgControl implements OnChanges,
     this.valueAccessor = selectValueAccessor(this, valueAccessors);
   }
 
-  ngOnChanges(changes: {[key: string]: SimpleChange}) {
+  ngOnChanges(changes: SimpleChanges) {
     if (!this._added) {
       this.formDirective.addControl(this);
       this._added = true;
diff --git a/modules/@angular/common/src/forms/directives/ng_form_control.ts b/modules/@angular/common/src/forms/directives/ng_form_control.ts
index 0ec1598396..1389990992 100644
--- a/modules/@angular/common/src/forms/directives/ng_form_control.ts
+++ b/modules/@angular/common/src/forms/directives/ng_form_control.ts
@@ -1,6 +1,6 @@
 import {
   OnChanges,
-  SimpleChange,
+  SimpleChanges,
   Directive,
   forwardRef,
   Inject,
@@ -100,7 +100,7 @@ export class NgFormControl extends NgControl implements OnChanges {
     this.valueAccessor = selectValueAccessor(this, valueAccessors);
   }
 
-  ngOnChanges(changes: {[key: string]: SimpleChange}): void {
+  ngOnChanges(changes: SimpleChanges): void {
     if (this._isControlChanged(changes)) {
       setUpControl(this.form, this);
       this.form.updateValueAndValidity({emitEvent: false});
diff --git a/modules/@angular/common/src/forms/directives/ng_form_model.ts b/modules/@angular/common/src/forms/directives/ng_form_model.ts
index 6924a85b90..8b654161e0 100644
--- a/modules/@angular/common/src/forms/directives/ng_form_model.ts
+++ b/modules/@angular/common/src/forms/directives/ng_form_model.ts
@@ -1,5 +1,5 @@
 import {
-  SimpleChange,
+  SimpleChanges,
   OnChanges,
   Directive,
   forwardRef,
@@ -116,7 +116,7 @@ export class NgFormModel extends ControlContainer implements Form,
     super();
   }
 
-  ngOnChanges(changes: {[key: string]: SimpleChange}): void {
+  ngOnChanges(changes: SimpleChanges): void {
     this._checkFormPresent();
     if (StringMapWrapper.contains(changes, "form")) {
       var sync = composeValidators(this._validators);
diff --git a/modules/@angular/common/src/forms/directives/ng_model.ts b/modules/@angular/common/src/forms/directives/ng_model.ts
index accf55a2ef..c36dd7dbea 100644
--- a/modules/@angular/common/src/forms/directives/ng_model.ts
+++ b/modules/@angular/common/src/forms/directives/ng_model.ts
@@ -1,6 +1,6 @@
 import {
   OnChanges,
-  SimpleChange,
+  SimpleChanges,
   Directive,
   forwardRef,
   Inject,
@@ -72,7 +72,7 @@ export class NgModel extends NgControl implements OnChanges {
     this.valueAccessor = selectValueAccessor(this, valueAccessors);
   }
 
-  ngOnChanges(changes: {[key: string]: SimpleChange}) {
+  ngOnChanges(changes: SimpleChanges) {
     if (!this._added) {
       setUpControl(this._control, this);
       this._control.updateValueAndValidity({emitEvent: false});
diff --git a/modules/@angular/compiler/test/metadata_resolver_spec.ts b/modules/@angular/compiler/test/metadata_resolver_spec.ts
index abac4b9b16..02e2312d00 100644
--- a/modules/@angular/compiler/test/metadata_resolver_spec.ts
+++ b/modules/@angular/compiler/test/metadata_resolver_spec.ts
@@ -28,7 +28,7 @@ import {
   AfterContentChecked,
   AfterViewInit,
   AfterViewChecked,
-  SimpleChange,
+  SimpleChanges,
   provide
 } from '@angular/core';
 
@@ -141,7 +141,7 @@ class ComponentWithoutModuleId {
 class ComponentWithEverything implements OnChanges,
     OnInit, DoCheck, OnDestroy, AfterContentInit, AfterContentChecked, AfterViewInit,
     AfterViewChecked {
-  ngOnChanges(changes: {[key: string]: SimpleChange}): void {}
+  ngOnChanges(changes: SimpleChanges): void {}
   ngOnInit(): void {}
   ngDoCheck(): void {}
   ngOnDestroy(): void {}
diff --git a/modules/@angular/core/src/change_detection.ts b/modules/@angular/core/src/change_detection.ts
index f67ef4e4d5..90f99e2cca 100644
--- a/modules/@angular/core/src/change_detection.ts
+++ b/modules/@angular/core/src/change_detection.ts
@@ -11,6 +11,7 @@ export {
 
   WrappedValue,
   SimpleChange,
+  SimpleChanges,
   PipeTransform,
   DefaultIterableDiffer,
   IterableDiffers,
diff --git a/modules/@angular/core/src/change_detection/change_detection.ts b/modules/@angular/core/src/change_detection/change_detection.ts
index cdd341b6e2..9377fdb098 100644
--- a/modules/@angular/core/src/change_detection/change_detection.ts
+++ b/modules/@angular/core/src/change_detection/change_detection.ts
@@ -41,6 +41,7 @@ export {
   looseIdentical,
   uninitialized
 } from './change_detection_util';
+export {SimpleChanges} from '../metadata/lifecycle_hooks';
 
 /**
  * Structural diffing for `Object`s and `Map`s.
diff --git a/modules/@angular/core/src/metadata/lifecycle_hooks.ts b/modules/@angular/core/src/metadata/lifecycle_hooks.ts
index 0c4d384142..1b1ad99699 100644
--- a/modules/@angular/core/src/metadata/lifecycle_hooks.ts
+++ b/modules/@angular/core/src/metadata/lifecycle_hooks.ts
@@ -11,6 +11,15 @@ export enum LifecycleHooks {
   AfterViewChecked
 }
 
+/**
+ * A `changes` object whose keys are property names and
+ * values are instances of {@link SimpleChange}. See {@link OnChanges}
+ */
+export interface SimpleChanges {[propName: string]: SimpleChange};
+
+/**
+ * @internal
+ */
 export var LIFECYCLE_HOOKS_VALUES = [
   LifecycleHooks.OnInit,
   LifecycleHooks.OnDestroy,
@@ -53,7 +62,7 @@ export var LIFECYCLE_HOOKS_VALUES = [
  * class MyComponent implements OnChanges {
  *   @Input() myProp: any;
  *
- *   ngOnChanges(changes: {[propName: string]: SimpleChange}) {
+ *   ngOnChanges(changes: SimpleChanges) {
  *     console.log('ngOnChanges - myProp = ' + changes['myProp'].currentValue);
  *   }
  * }
@@ -72,7 +81,7 @@ export var LIFECYCLE_HOOKS_VALUES = [
  * bootstrap(App).catch(err => console.error(err));
  * ```
  */
-export abstract class OnChanges { abstract ngOnChanges(changes: {[key: string]: SimpleChange}); }
+export abstract class OnChanges { abstract ngOnChanges(changes: SimpleChanges); }
 
 /**
  * Implement this interface to execute custom initialization logic after your directive's
diff --git a/modules/@angular/upgrade/src/downgrade_ng2_adapter.ts b/modules/@angular/upgrade/src/downgrade_ng2_adapter.ts
index dfbf35bc9b..3e4502fcaa 100644
--- a/modules/@angular/upgrade/src/downgrade_ng2_adapter.ts
+++ b/modules/@angular/upgrade/src/downgrade_ng2_adapter.ts
@@ -6,6 +6,7 @@ import {
   ComponentFactory,
   ComponentRef,
   SimpleChange,
+  SimpleChanges,
   ReflectiveInjector
 } from '@angular/core';
 import {NG1_SCOPE} from './constants';
@@ -19,7 +20,7 @@ const INITIAL_VALUE = {
 export class DowngradeNg2ComponentAdapter {
   component: any = null;
   inputChangeCount: number = 0;
-  inputChanges: {[key: string]: SimpleChange} = null;
+  inputChanges: SimpleChanges = null;
   componentRef: ComponentRef<any> = null;
   changeDetector: ChangeDetectorRef = null;
   componentScope: angular.IScope;
diff --git a/modules/@angular/upgrade/src/upgrade_ng1_adapter.ts b/modules/@angular/upgrade/src/upgrade_ng1_adapter.ts
index a45768fe7e..2935ae49aa 100644
--- a/modules/@angular/upgrade/src/upgrade_ng1_adapter.ts
+++ b/modules/@angular/upgrade/src/upgrade_ng1_adapter.ts
@@ -7,6 +7,7 @@ import {
   OnInit,
   OnChanges,
   SimpleChange,
+  SimpleChanges,
   Type
 } from '@angular/core';
 import {
@@ -248,7 +249,7 @@ class UpgradeNg1ComponentAdapter implements OnInit, OnChanges, DoCheck {
     }
   }
 
-  ngOnChanges(changes: {[name: string]: SimpleChange}) {
+  ngOnChanges(changes: SimpleChanges) {
     for (var name in changes) {
       if ((<Object>changes).hasOwnProperty(name)) {
         var change: SimpleChange = changes[name];