 Kant’s most influential positions in moral philosophy are found in The Groundwork of the Metaphysics of Morals (hereafter, “Groundwork”) but he developed, enriched, and in some cases modified those views in later works such as The Critique of Practical Reason, The Metaphysics of Morals, Anthropology from a Pragmatic Point of View, Religion within the Boundaries of Mere Reason as well as his essays on history and related topics. Kant’s Lectures on Ethics, which were lecture notes taken by three of his students on the courses he gave in moral philosophy, also include relevant material for understanding his views. We will mainly focus on the foundational doctrines of the Groundwork, even though in recent years some scholars have become dissatisfied with this standard approach to Kant’s views and have turned their attention to the later works. We find the standard approach most illuminating, though we will highlight important positions from the later works where needed.