Immanuel Kant's "Groundwork for the Metaphysics of Morals" is one of the most important texts in the history of ethics. In it Kant searches for the supreme principle of morality and argues for a conception of the moral life that has made this work a continuing source of controversy and an object of reinterpretation for over two centuries. This new edition of Kant's work provides a translation that seeks to be faithful to the German original and is fully annotated. There are also four essays by well-known scholars that discuss Kant's views and the philosophical issues raised by his work. J.B. Schneewind defends the continuing interest in Kantian ethics by examining its historical relation both to the ethical thought that preceded it and to its influence on the ethical theories that came after it; Marcia Baron sheds light on Kant's famous views about moral motivation; and Shelly Kagan and Allen W. Wood advocate contrasting interpretations of Kantian ethics and its practical implications.