diff --git a/knockout-transformations/knockout-transformations-tests.ts b/knockout-transformations/knockout-transformations-tests.ts
new file mode 100644
index 0000000000..6b15b3ca01
--- /dev/null
+++ b/knockout-transformations/knockout-transformations-tests.ts
@@ -0,0 +1,163 @@
+/// <reference path="../knockout/knockout.d.ts" />
+/// <reference path="knockout-transformations.d.ts" />
+
+// Test map
+var sourceItems: KnockoutObservableArray<number> = ko.observableArray([1, 2, 3, 4, 5]);
+var squares: KnockoutObservableArray<number> = sourceItems.map(function (x) { return x * x; });
+var squaresAsStrings: KnockoutObservableArray<string> = sourceItems.map(function (x) { return (x * x).toString(); });
+
+sourceItems.push(6);
+// 'squares' has automatically updated and now contains [1, 4, 9, 16, 25, 36]
+// 'squaresAsStrings' has automatically updated and now contains ['1', '4', '9', '16', '25', '36']
+
+sourceItems.reverse();
+// 'squares' now contains [36, 25, 16, 9, 4, 1]
+// 'squaresAsStrings' now contains ['36', '25', '16', '9', '4', '1']
+
+// Test Filtering
+
+var evenSquares: KnockoutObservableArray<number> = squares.filter(function (x) { return x % 2 === 0; });
+// evenSquares is now an observable containing [36, 16, 4]
+
+sourceItems.push(9);
+// This has no effect on evenSquares, because 9*9=81 is odd
+
+sourceItems.push(10);
+// evenSquares now contains [36, 16, 4, 100]
+
+var sortedEvenSquares: KnockoutObservableArray<number> = evenSquares.sortBy(function (evenSquare, descending) {
+    return descending(evenSquare);
+});
+// sortedEvenSquares now contains [100, 36, 16, 4]
+
+class Person {
+    public name: KnockoutObservable<string>;
+    public yearOfBirth: KnockoutObservable<number>;
+
+    constructor(name: string, yearOfBirth: number) {
+        this.name = ko.observable(name);
+        this.yearOfBirth = ko.observable(yearOfBirth);
+    }
+}
+
+var persons: KnockoutObservableArray<Person> = ko.observableArray([
+    new Person("Marilyn Monroe", 1926),
+    new Person("Abraham Lincoln", 1809),
+    new Person("Mother Teresa", 1910),
+    new Person("John F. Kennedy", 1917),
+    new Person("Martin Luther King", 1929),
+    new Person("Nelson Mandela", 1918),
+    new Person("Winston Churchill", 1874),
+    new Person("Bill Gates", 1955),
+    new Person("Muhammad Ali", 1942),
+    new Person("Mahatma Gandhi", 1869),
+    new Person("Queen Elizabeth II", 1926)
+]);
+
+// Persons sorted by name
+var sortedByName: KnockoutObservableArray<Person> = persons.sortBy(function (person) {
+    return person.name();
+});
+
+// sortedByName now contains
+// [
+//     new Person("Abraham Lincoln", 1809),
+//     new Person("Bill Gates", 1955),
+//     new Person("John F. Kennedy", 1917),
+//     new Person("Mahatma Gandhi", 1869),
+//     new Person("Marilyn Monroe", 1926),
+//     new Person("Martin Luther King", 1929),
+//     new Person("Mother Teresa", 1910),
+//     new Person("Muhammad Ali", 1942)
+//     new Person("Nelson Mandela", 1918),
+//     new Person("Queen Elizabeth II", 1926),
+//     new Person("Winston Churchill", 1874),
+// ]
+
+// Persons sorted by year of birth descending and then by name
+var sortedByYearOfBirthAndThenName: KnockoutObservableArray<Person> = persons.sortBy(function (person, descending) {
+    return [descending(person.yearOfBirth()), person.name()];
+});
+
+// sortedByYearOfBirthAndThenName now contains
+// [
+//     new Person("Abraham Lincoln", 1809),
+//     new Person("Mahatma Gandhi", 1869),
+//     new Person("Winston Churchill", 1874),
+//     new Person("Mother Teresa", 1910),
+//     new Person("John F. Kennedy", 1917),
+//     new Person("Nelson Mandela", 1918),
+//     new Person("Martin Luther King", 1929),
+//     new Person("Bill Gates", 1955),
+//     new Person("Marilyn Monroe", 1926),
+//     new Person("Queen Elizabeth II", 1926),
+//     new Person("Muhammad Ali", 1942)
+// ]
+
+var squareIndex: KnockoutObservable<{ [index: string]: number[] }> = squares.indexBy(function (square) {
+    return square % 2 === 0 ? 'even' : 'odd';
+});
+
+// squareIndex now contains
+// { even: [36, 16, 4], odd: [25, 9, 1] }
+
+// Persons indexed by year of birth
+var personsIndexedByYearBirth: KnockoutObservable<{ [index: number]: Person[] }> = persons.indexBy(function (person) {
+    return person.yearOfBirth();
+});
+
+// personsIndexedByYearBirth now contains
+// {
+//     1809: [new Person("Abraham Lincoln", 1809)],
+//     1869: [new Person("Mahatma Gandhi", 1869)],
+//     1874: [new Person("Winston Churchill", 1874)],
+//     1910: [new Person("Mother Teresa", 1910)],
+//     1917: [new Person("John F. Kennedy", 1917)],
+//     1918: [new Person("Nelson Mandela", 1918)],
+//     1929: [new Person("Martin Luther King", 1929)],
+//     1955: [new Person("Bill Gates", 1955)],
+//     1926: [new Person("Marilyn Monroe", 1926),
+//            new Person("Queen Elizabeth II", 1926)],
+//     1942: [new Person("Muhammad Ali", 1942)]
+// }
+
+// Persons indexed uniquely by name.
+// Notice unique indexes requires items to map to distint keys;
+// otherwise an exception is thrown.
+var personsIndexedByName: KnockoutObservable<{ [name: string]: Person }> = persons.uniqueIndexBy(function (person) {
+    return person.name();
+});
+
+// personsIndexedByName now contains
+// {
+//     "Abraham Lincoln": new Person("Abraham Lincoln", 1809),
+//     "Mahatma Gandhi": new Person("Mahatma Gandhi", 1869),
+//     "Winston Churchill": new Person("Winston Churchill", 1874),
+//     "Mother Teresa": new Person("Mother Teresa", 1910),
+//     "John F. Kennedy": new Person("John F. Kennedy", 1917),
+//     "Nelson Mandela": new Person("Nelson Mandela", 1918),
+//     "Martin Luther King": new Person("Martin Luther King", 1929),
+//     "Bill Gates": new Person("Bill Gates", 1955),
+//     "Marilyn Monroe": new Person("Marilyn Monroe", 1926),
+//     "Queen Elizabeth II": new Person("Queen Elizabeth II", 1926),
+//     "Muhammad Ali": new Person("Muhammad Ali", 1942)
+// }
+
+var texts: KnockoutObservableArray<string> = ko.observableArray(['foo', 'bar', 'baz', 'qux', 'quux']);
+// Index texts by
+var indexedTexts: KnockoutObservable<{ [suffixOrPrefix: string]: string[] }> = texts.indexBy(function (text) {
+    var firstLetter = text[0];
+    var lastLetter = text[text.length - 1];
+    return [firstLetter, lastLetter];
+});
+
+// indexedTexts now contains
+// {
+//     f: ['foo'],
+//     b: ['bar', 'baz'],
+//     q: ['qux', 'quux'],
+//     o: ['foo'],
+//     r: ['bar'],
+//     z: ['baz'],
+//     x: ['qux', 'quux']
+// }
diff --git a/knockout-transformations/knockout-transformations.d.ts b/knockout-transformations/knockout-transformations.d.ts
new file mode 100644
index 0000000000..b599c7d699
--- /dev/null
+++ b/knockout-transformations/knockout-transformations.d.ts
@@ -0,0 +1,16 @@
+// Type definitions for knockout-transformations 2.0.0
+// Project: https://github.com/One-com/knockout-transformations
+// Definitions by: John Reilly <https://github.com/johnnyreilly>, Wim Looman <https://github.com/Nemo157>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="../knockout/knockout.d.ts" />
+
+interface KnockoutObservableArrayFunctions<T> {
+    map<TResult>(mapping: (value: T) => TResult): KnockoutObservableArray<TResult>;
+    filter(predicate: (value: T) => boolean): KnockoutObservableArray<T>;
+    sortBy(sorter: (value: T, descending: (sorter: any) => any) => any): KnockoutObservableArray<T>;
+    indexBy(indexer: (value: T) => string): KnockoutObservable<{ [index: string]: T[] }>;
+    indexBy(indexer: (value: T) => string[]): KnockoutObservable<{ [index: string]: T[] }>;
+    indexBy(indexer: (value: T) => any): KnockoutObservable<any>;
+    uniqueIndexBy(indexer: (value: T) => string): KnockoutObservable<{ [index: string]: T }>;
+}