This book analyses the moral theory of the seventh century Indian Mahayana master, Santideva. Santideva is the author of the well-known religious poem the Bodhicaryavatara (Entering the Path of Enlightenment), as well as the significant, but relatively overlooked, Siksasamuccaya (Compendium of Teachings). Both of these works describe the nature and path of the bodhisattva, the altruistic spiritual ideal especially exalted in Mahayana literature. With particular focus on the Siksasamuccaya, this work offers a response to three questions: What is Santideva's moral theory? How does it compare to other analyses of Buddhist ethics? Can one moral theory adequately describe Buddhist moral thought?