diff --git a/Definitions/underscore.d.ts b/Definitions/underscore.d.ts
new file mode 100644
index 000000000..6f5779f46
--- /dev/null
+++ b/Definitions/underscore.d.ts
@@ -0,0 +1,158 @@
+// Type definitions for Underscore 1.4.1
+// https://github.com/borisyankov/DefinitelyTyped
+
+interface KeyValuePair {
+    key: string;
+    value: any;
+}
+
+interface TemplateSettings {
+    evaluate?: RegExp;
+    interpolate?: RegExp;
+    escape?: RegExp;
+}
+
+interface UnderscoreStatic {
+
+    /****
+     Collections
+    *****/
+    each(list: any[], iterator: any, context?: any): any[]; // interface Iterator = (element, index, list) => any;
+    each(obj: any, iterator: any, context?: any): any[]; // (value, key, list)
+    forEach(list: any[], iterator: any, context?: any): any[];
+    forEach(obj: any, iterator: any, context?: any): any[];
+
+    map(list: any[], iterator: any, context?: any): any[];
+    map(obj: any, iterator: any, context?: any): any[];
+    collect(list: any[], iterator: any, context?: any): any[];
+    collect(obj: any, iterator: any, context?: any): any[];
+
+    reduce(list: any[], iterator: any, memo: any, context?: any): any[];
+    inject(list: any[], iterator: any, memo: any, context?: any): any[];
+    foldl(list: any[], iterator: any, memo: any, context?: any): any[];
+
+    reduceRight(list: any[], iterator: any, memo: any, context?: any): any[];
+    foldr(list: any[], iterator: any, memo: any, context?: any): any[];
+    find(list: any[], iterator: any, context?: any): any;
+    detect(list: any[], iterator: any, context?: any): any;
+    filter(list: any[], iterator: any, context?: any): any[];
+    select(list: any[], iterator: any, context?: any): any[];
+    where(list: any[], properties: any): any[];
+    reject(list: any[], iterator: any, context?: any): any[];
+    all(list: any[], iterator: any, context?: any): bool;
+    _any(list: any[], iterator?: any, context?: any): bool;
+    contains(list: any, value: any): bool;
+    contains(list: any[], value: any): bool;
+
+    invoke(list: any[], methodName: string, arguments: any[]): any;
+    invoke(obj: any, methodName: string, ...arguments: any[]): any;
+
+    pluck(list: any[], propertyName: string): string[];
+    max(list: any[], iterator?: any, context?: any): any;
+    min(list: any[], iterator?: any, context?: any): any;
+    sortBy(list: any[], iterator?: any, context?: any): any;
+    groupBy(list: any[], iterator: any): any;
+    countBy(list: any[], iterator: any): any;
+    shuffle(list: any[]): any[];
+    toArray(list: any): any[];
+    size(list: any): number;
+
+    /****
+     Arrays
+    *****/
+    first(array: any[], n?: number): any;
+    head(array: any[], n?: number): any;
+    take(array: any[], n?: number): any;
+    initial(array: any[], n?: number): any[];
+    last(array: any[], n?: number): any;
+    rest(array: any[], n?: number): any[];
+    tail(array: any[], n?: number): any[];
+    drop(array: any[], n?: number): any[];
+    compact(array: any[]): any[];
+    flatten(array: any[], shallow?: bool): any[];
+    without(array: any[], ...values: any[]): any[];
+    union(...arrays: any[]): any[];
+    intersection(...arrays: any[]): any[];
+    difference(array: any[], ...others: any[]): any[];
+    uniq(array: any[], isSorted?: bool, iterator?: any): any[];
+    zip(...arrays: any[]): any[];
+    object(list: any[], values: any[]): any;
+    indexOf(array: any[], value: any, isSorted?: bool): number;
+    lastIndexOf(array: any[], value: any, fromIndex?: number): number;
+    sortedIndex(list: any[], valueL: any, iterator?: any): number;
+    range(stop: number): any[];
+    range(start: number, stop: number, step?: number): any[];
+
+    /****
+     Functions
+    *****/
+    bind(func: any, context: any, ...arguments: any[]): () => any;
+    bindAll(obj: any, ...methodNames: string[]): any;
+    memoize(func: any, hashFunction?: any): any;
+    defer(func: () => any);
+    delay(func: any, wait: number, ...arguments: any[]): any;
+    delay(func: any, ...arguments: any[]): any;
+    throttle(func: any, wait: number): any;
+    debounce(func: any, wait: number, immediate?: bool): any;
+    once(func: any): any;
+    after(count: number, func: any): any;
+    wrap(func: any, wrapper: any): () => any;
+    compose(...functions: any[]): any;
+
+    /****
+     Objects
+    *****/
+    keys(object: any): any[];
+    values(object: any): any[];
+    pairs(object: any): KeyValuePair[];
+    invert(object: any): any[];
+    functions(object: any): string[];
+    methods(object: any): string[];
+    extend(destination: any, sources: any): any;
+    pick(object: any, ...keys: string[]): any;
+    omit(object: any, key: string): any;
+    omit(object: any, keys: string[]): any;
+    defaults(object: any, defaults: any): any;
+    clone(object: any): any;
+    tap(object: any, interceptor: any): any;
+    has(object: any, key: string): bool;
+    isEqual(object: any, other: any): bool;
+    isEmpty(object: any): bool;
+    isElement(object: any): bool;
+    isArray(object: any): bool;
+    isObject(value: any): bool;
+    isArguments(object: any): bool;
+    isFunction(object: any): bool;
+    isString(object: any): bool;
+    isNumber(object: any): bool;
+    isFinite(object: any): bool;
+    isBoolean(object: any): bool;
+    isDate(object: any): bool;
+    isRegExp(object: any): bool;
+    isNaN(object: any): bool;
+    isNull(object: any): bool;
+    isUndefined(value: any): bool;
+
+    /****
+     Utility
+    *****/
+    noConflict(): UnderscoreStatic;
+    identity(value: any): any;
+    times(n: number, iterator: any, context?: any): any[];
+    random(min: number, max: number): number;
+    mixin(object: any): any;
+    uniqueId(prefix: string): string;
+    uniqueId(): number;
+    escape(string: string): string;
+    result(object: any, property: any): any;
+    templateSettings: TemplateSettings;
+    template(templateString: string, data?: any, settings?: any): (data: any) => string;
+
+    /****
+     Chaining
+    *****/
+    chain(obj: any): any;
+    // (obj).value()
+}
+
+declare var _: UnderscoreStatic;
\ No newline at end of file
diff --git a/Tests/underscore.ts b/Tests/underscore.ts
new file mode 100644
index 000000000..895307b98
--- /dev/null
+++ b/Tests/underscore.ts
@@ -0,0 +1,249 @@
+/// <reference path="../Definitions/underscore.d.ts" />
+
+declare var $: any;
+
+function alert(thing: any) {
+    $('#content').append('<div>' + thing + '</div>');
+}
+
+$(() => {
+
+    _.each([1, 2, 3], (num) => alert(num));
+    _.each({ one: 1, two: 2, three: 3 }, (num, key) => alert(num));
+
+    _.map([1, 2, 3], (num) => num * 3);
+    _.map({ one: 1, two: 2, three: 3 }, (num, key) => num * 3);
+
+    var sum = _.reduce([1, 2, 3], (memo, num) => memo + num, 0);
+    // alert(sum);
+
+    var list = [[0, 1], [2, 3], [4, 5]];
+    var flat = _.reduceRight(list, (a, b) => a.concat(b), []);
+    // alert(flat);
+
+    var even = _.find([1, 2, 3, 4, 5, 6], (num) => num % 2 == 0);
+
+    var evens = _.filter([1, 2, 3, 4, 5, 6], (num) => num % 2 == 0);
+
+    var listOfPlays = [{ title: "Cymbeline", author: "Shakespeare", year: 1611 }, { title: "The Tempest", author: "Shakespeare", year: 1611 }, { title: "Other", author: "Not Shakespeare", year: 2012 }];
+    _.where(listOfPlays, { author: "Shakespeare", year: 1611 });
+
+    var odds = _.reject([1, 2, 3, 4, 5, 6], (num) => num % 2 == 0);
+
+    _.all([true, 1, null, 'yes'], _.identity);
+
+    _._any([null, 0, 'yes', false]);
+
+    _.contains([1, 2, 3], 3);
+
+    _.invoke([[5, 1, 7], [3, 2, 1]], 'sort');
+
+    var stooges = [{ name: 'moe', age: 40 }, { name: 'larry', age: 50 }, { name: 'curly', age: 60 }];
+    _.pluck(stooges, 'name');
+
+    var stooges = [{ name: 'moe', age: 40 }, { name: 'larry', age: 50 }, { name: 'curly', age: 60 }];
+    _.max(stooges, (stooge) => stooge.age);
+
+    var numbers = [10, 5, 100, 2, 1000];
+    _.min(numbers);
+
+    _.sortBy([1, 2, 3, 4, 5, 6], (num) => Math.sin(num));
+
+    _.groupBy([1.3, 2.1, 2.4], (num) => Math.floor(num));
+    _.groupBy(['one', 'two', 'three'], 'length');
+
+    _.countBy([1, 2, 3, 4, 5], (num) => num % 2 == 0 ? 'even' : 'odd');
+
+    _.shuffle([1, 2, 3, 4, 5, 6]);
+
+    //(function(){ return _.toArray(arguments).slice(1); })(1, 2, 3, 4);
+
+    _.size({ one: 1, two: 2, three: 3 });
+
+    ///////////////////////////////////////////////////////////////////////////////////////
+
+    _.first([5, 4, 3, 2, 1]);
+    _.initial([5, 4, 3, 2, 1]);
+    _.last([5, 4, 3, 2, 1]);
+    _.rest([5, 4, 3, 2, 1]);
+    _.compact([0, 1, false, 2, '', 3]);
+    //_.flatten([1, [2], [3, [[4]]]]);
+    //_.flatten([1, [2], [3, [[4]]]], true);
+    _.without([1, 2, 1, 0, 3, 1, 4], 0, 1);
+    _.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
+    _.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]);
+    _.difference([1, 2, 3, 4, 5], [5, 2, 10]);
+    _.uniq([1, 2, 1, 3, 1, 4]);
+    _.zip(['moe', 'larry', 'curly'], [30, 40, 50], [true, false, false]);
+    _.object(['moe', 'larry', 'curly'], [30, 40, 50]);
+    // _.object([['moe', 30], ['larry', 40], ['curly', 50]]);
+    _.indexOf([1, 2, 3], 2);
+    _.lastIndexOf([1, 2, 3, 1, 2, 3], 2);
+    _.sortedIndex([10, 20, 30, 40, 50], 35);
+    _.range(10);
+    _.range(1, 11);
+    _.range(0, 30, 5);
+    _.range(0, 30, 5);
+    _.range(0);
+
+    ///////////////////////////////////////////////////////////////////////////////////////
+
+    var func = function (greeting) { return greeting + ': ' + this.name };
+    func = _.bind(func, { name: 'moe' }, 'hi');
+    // func();
+
+    var buttonView = {
+        label: 'underscore',
+        onClick: function () { alert('clicked: ' + this.label); },
+        onHover: function () { console.log('hovering: ' + this.label); }
+    };
+    _.bindAll(buttonView);
+    //$('#underscore_button').bind('click', buttonView.onClick);
+
+    var fibonacci = _.memoize(function (n) {
+        return n < 2 ? n : fibonacci(n - 1) + fibonacci(n - 2);
+    });
+
+    var log = _.bind(console.log, console);
+    _.delay(log, 1000, 'logged later');
+
+    _.defer(function () { alert('deferred'); });
+
+    var updatePosition = () => alert('updating position...');
+    var throttled = _.throttle(updatePosition, 100);
+    $(window).scroll(throttled);
+
+    var calculateLayout = () => alert('calculating layout...');
+    var lazyLayout = _.debounce(calculateLayout, 300);
+    $(window).resize(lazyLayout);
+
+    var createApplication = () => alert('creating application...');
+    var initialize = _.once(createApplication);
+    initialize();
+    initialize();
+
+    var notes: any[];
+    var render = () => alert("rendering...");
+    var renderNotes = _.after(notes.length, render);
+    _.each(notes, (note) => note.asyncSave({ success: renderNotes }));
+
+    var hello = function (name) { return "hello: " + name; };
+    hello = _.wrap(hello, (func) => { return "before, " + func("moe") + ", after"; });
+    // hello();
+
+    var greet = function (name) { return "hi: " + name; };
+    var exclaim = function (statement) { return statement + "!"; };
+    var welcome = _.compose(exclaim, greet);
+    welcome('moe');
+
+    ///////////////////////////////////////////////////////////////////////////////////////
+
+    _.keys({ one: 1, two: 2, three: 3 });
+    _.values({ one: 1, two: 2, three: 3 });
+    _.pairs({ one: 1, two: 2, three: 3 });
+    _.invert({ Moe: "Moses", Larry: "Louis", Curly: "Jerome" });
+    _.functions(_);
+    _.extend({ name: 'moe' }, { age: 50 });
+    _.pick({ name: 'moe', age: 50, userid: 'moe1' }, 'name', 'age');
+    _.omit({ name: 'moe', age: 50, userid: 'moe1' }, 'userid');
+
+    var iceCream = { flavor: "chocolate" };
+    _.defaults(iceCream, { flavor: "vanilla", sprinkles: "lots" });
+
+    _.clone({ name: 'moe' });
+
+    _.chain([1, 2, 3, 200])
+      .filter(function (num) { return num % 2 == 0; })
+      .tap(alert)
+      .map(function (num) { return num * num })
+      .value();
+
+    _.has({ a: 1, b: 2, c: 3 }, "b");
+
+    var moe = { name: 'moe', luckyNumbers: [13, 27, 34] };
+    var clone = { name: 'moe', luckyNumbers: [13, 27, 34] };
+    moe == clone;
+    _.isEqual(moe, clone);
+
+    _.isEmpty([1, 2, 3]);
+    _.isEmpty({});
+
+    _.isElement($('body')[0]);
+
+    (function () { return _.isArray(arguments); })();
+    _.isArray([1, 2, 3]);
+
+    _.isObject({});
+    _.isObject(1);
+
+
+    // (() => { return _.isArguments(arguments); })(1, 2, 3);
+    _.isArguments([1, 2, 3]);
+
+    _.isFunction(alert);
+
+    _.isString("moe");
+
+    _.isNumber(8.4 * 5);
+
+    _.isFinite(-101);
+
+    _.isFinite(-Infinity);
+
+    _.isBoolean(null);
+
+    _.isDate(new Date());
+
+    _.isRegExp(/moe/);
+
+    _.isNaN(NaN);
+    isNaN(undefined);
+    _.isNaN(undefined);
+
+    _.isNull(null);
+    _.isNull(undefined);
+
+    // _.isUndefined(window.missingVariable);
+
+    ///////////////////////////////////////////////////////////////////////////////////////
+
+    var underscore = _.noConflict();
+
+    var moe2 = { name: 'moe' };
+    moe2 === _.identity(moe);
+
+    // _(3).times(function(n){ genie.grantWishNumber(n); });
+
+    _.random(0, 100);
+
+    _.mixin({
+        capitalize: function (string) {
+            return string.charAt(0).toUpperCase() + string.substring(1).toLowerCase();
+        }
+    });
+    // _("fabio").capitalize();
+
+    _.uniqueId('contact_');
+
+    _.escape('Curly, Larry & Moe');
+
+    var object = { cheese: 'crumpets', stuff: function () { return 'nonsense'; } };
+    _.result(object, 'cheese');
+
+    _.result(object, 'stuff');
+
+    var compiled = _.template("hello: <%= name %>");
+    compiled({ name: 'moe' });
+    var list2 = "<% _.each(people, function(name) { %> <li><%= name %></li> <% }); %>";
+    _.template(list2, { people: ['moe', 'curly', 'larry'] });
+    var template = _.template("<b><%- value %></b>");
+    template({ value: '<script>' });
+    var compiled = _.template("<% print('Hello ' + epithet); %>");
+    compiled({ epithet: "stooge" });
+    _.templateSettings = {
+        interpolate: /\{\{(.+?)\}\}/g
+    };
+    var template = _.template("Hello {{ name }}!");
+    template({ name: "Mustache" });
+    _.template("Using 'with': <%= data.answer %>", { answer: 'no' }, { variable: 'data' });
+});