diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index 39dbe3d2f..290a3c8ca 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -154,6 +154,7 @@ All definitions files include a header with the author and editors, so at some p
 * [Jasmine-data_driven_tests](https://github.com/gburghardt/jasmine-data_driven_tests) (by [Anthony MacKinnon](https://github.com/AnthonyMacKinnon))
 * [Jasmine-jQuery](https://github.com/velesin/jasmine-jquery) (by [Gregor Stamac](https://github.com/gstamac))
 * [jDataView](https://github.com/jDataView/jDataView) (by [Ingvar Stepanyan](https://github.com/RReverser))
+* [Jest](http://facebook.github.io/jest/) (by [Joshua Smith](https://github.com/Josh211ua))
 * [JointJS](http://www.jointjs.com/) (by [Aidan Reel](http://github.com/areel))
 * [jQRangeSlider](http://ghusse.github.com/jQRangeSlider) (by [Dániel Tar](https://github.com/qcz))
 * [jQuery](http://jquery.com/) (from TypeScript samples)
diff --git a/jest/jest-tests.ts b/jest/jest-tests.ts
new file mode 100644
index 000000000..764daf142
--- /dev/null
+++ b/jest/jest-tests.ts
@@ -0,0 +1,123 @@
+/// <reference path="jest.d.ts" />
+
+// Tests based on the Jest website
+jest.dontMock('../sum');
+
+describe('sum', function() {
+    it('adds 1 + 2 to equal 3', function() {
+        var sum: (a: number, b: number) => number = require('../sum');
+        expect(sum(1, 2)).toBe(3);
+    });
+});
+
+describe('fetchCurrentUser', function() {
+    it('calls the callback when $.ajax requests are finished', function() {
+        var $ = require('jquery');
+        var fetchCurrentUser = require('../fetchCurrentUser');
+
+        // Create a mock function for our callback
+        var callback = jest.genMockFunction();
+        fetchCurrentUser(callback);
+
+        // Now we emulate the process by which `$.ajax` would execute its own
+        // callback
+        $.ajax.mock.calls[0 /*first call*/][0 /*first argument*/].success({
+            firstName: 'Bobby',
+            lastName: '");DROP TABLE Users;--'
+        });
+
+        // And finally we assert that this emulated call by `$.ajax` incurred a
+        // call back into the mock function we provided as a callback
+        expect(callback.mock.calls[0/*first call*/][0/*first arg*/]).toEqual({
+            loggedIn: true,
+            fullName: 'Bobby ");DROP TABLE Users;--'
+        });
+    });
+});
+
+jest.dontMock('../displayUser.js')
+jest.dontMock('jquery');
+
+describe('displayUser', function() {
+    it('displays a user after a click', function() {
+        // Set up our document body
+        document.body.innerHTML =
+            '<div>' +
+            '  <span id="username" />' +
+            '  <button id="button" />' +
+            '</div>';
+
+        var displayUser = require('../displayUser');
+        var $ = require('jquery');
+        var fetchCurrentUser = require('../fetchCurrentUser');
+
+        // Tell the fetchCurrentUser mock function to automatically invoke
+        // its callback with some data
+        fetchCurrentUser.mockImplementation(function(cb: Function) {
+            cb({
+                loggedIn: true,
+                fullName: 'Johnny Cash'
+            });
+        });
+
+        // Use jquery to emulate a click on our button
+        $('#button').click();
+
+        // Assert that the fetchCurrentUser function was called, and that the
+        // #username span's innter text was updated as we'd it expect.
+        expect(fetchCurrentUser).toBeCalled();
+        expect($('#username').text()).toEqual('Johnny Cash - Logged In');
+    });
+});
+
+jest.dontMock('../CheckboxWithLabel.js');
+describe('CheckboxWithLabel', function() {
+    it('changes the text after click', function() {
+        var React = require('react/addons');
+        var CheckboxWithLabel = require('../CheckboxWithLabel.js');
+        var TestUtils = React.addons.TestUtils;
+
+        // Render a checkbox with label in the document
+        var checkbox = TestUtils.renderIntoDocument(
+            CheckboxWithLabel({
+                    labelOn: "On",
+                    labelOff: "Off"
+                })
+        );
+
+        // Verify that it's Off by default
+        var label = TestUtils.findRenderedDOMComponentWithTag(
+            checkbox, 'label');
+        expect(label.getDOMNode().textContent).toEqual('Off');
+
+        // Simulate a click and verify that it is now On
+        var input = TestUtils.findRenderedDOMComponentWithTag(
+            checkbox, 'input');
+        TestUtils.Simulate.change(input);
+        expect(label.getDOMNode().textContent).toEqual('On');
+    });
+});
+
+function testInstances() {
+    var mockFn = jest.genMockFunction<Function>();
+    var a = new mockFn();
+    var b = new mockFn();
+
+    mockFn.mock.instances[0] === a; // true
+    mockFn.mock.instances[1] === b; // true
+}
+
+function testMockImplementation() {
+    var mockFn = jest.genMockFunction<Function>().mockImplementation(function (scalar:number):number {
+        return 42 + scalar;
+    });
+
+    var a = mockFn(0);
+    var b = mockFn(1);
+
+    a === 42; // true
+    b === 43; // true
+
+    mockFn.mock.calls[0][0] === 0; // true
+    mockFn.mock.calls[1][0] === 1; // true
+}
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diff --git a/jest/jest.d.ts b/jest/jest.d.ts
new file mode 100644
index 000000000..52d09f99e
--- /dev/null
+++ b/jest/jest.d.ts
@@ -0,0 +1,79 @@
+// Type definitions for Jest 0.1.18
+// Project: http://facebook.github.io/jest/
+// Definitions by: Asana <https://asana.com>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+declare function afterEach(fn: jest.EmptyFunction): void;
+declare function beforeEach(fn: jest.EmptyFunction): void;
+declare function describe(name: string, fn: jest.EmptyFunction): void;
+declare var it: jest.It;
+declare function pit(name: string, fn: jest.EmptyFunction): void;
+declare var require: jest.Require;
+declare function xdescribe(name: string, fn: jest.EmptyFunction): void;
+declare function xit(name: string, fn: jest.EmptyFunction): void;
+
+declare function expect(actual: any): jest.Matchers;
+
+declare module jest {
+    function autoMockOff(): void;
+    function autoMockOn(): void;
+    function clearAllTimers(): void;
+    function dontMock(moduleName: string): void;
+    function genMockFromModule<T>(moduleName: string): Mock<T>;
+    function genMockFunction<T>(): Mock<T>;
+    function genMockFn<T>(): Mock<T>;
+    function mock(moduleName: string): void;
+    function runAllTicks(): void;
+    function runAllTimers(): void;
+    function runOnlyPendingTimers(): void;
+    function setMock<T>(moduleName: string, moduleExports: T): void;
+
+    interface EmptyFunction {
+        (): void;
+    }
+
+    interface Matchers {
+        not: Matchers;
+        toThrow(expected?: any): boolean;
+        toBe(expected: any): boolean;
+        toEqual(expected: any): boolean;
+        toBeFalsy(): boolean;
+        toBeTruthy(): boolean;
+        toBeNull(): boolean;
+        toBeUndefined(): boolean;
+        toMatch(expected: RegExp): boolean;
+        toContain(expected: string): boolean;
+        toBeCloseTo(expected: number, delta: number): boolean;
+        toBeGreaterThen(expected: number): boolean;
+        toBeLessThen(expected: number): boolean;
+        toBeCalled(): boolean;
+        toBeCalledWith(...args: any[]): boolean;
+        lastCalledWith(...args: any[]): boolean;
+    }
+
+    interface It {
+        (name: string, fn: EmptyFunction): void;
+        only(name: string, fn: EmptyFunction): void;
+    }
+
+    interface Require {
+        (moduleName: string): any;
+        requireActual(moduleName: string): any;
+    }
+
+    interface Mock<T> {
+        new(): T;
+        mock: MockContext<T>;
+        mockClear(): void;
+        mockImplementation(fn: Function): Mock<T>;
+        mockImpl(fn: Function): Mock<T>;
+        mockReturnThis(): Mock<T>;
+        mockReturnValue(value: any): Mock<T>;
+        mockReturnValueOnce(value: any): Mock<T>;
+    }
+
+    interface MockContext<T> {
+        calls: any[][];
+        instances: T[];
+    }
+}
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