W. D. Ross is a major figure in the history of moral philosophy. In his 1930 masterpiece The Right and the Good, he gave the first sustained articulation and defense of a new position in moral theory: a moderate form of pluralistic deontology built around his most famous innovation, the concept of prima facie duty. Ross's theory of the good is also pluralistic and can be fruitfully contrasted both with Sidgwick's hedonism and with Moore's version of value pluralism. Ross is an exemplar of clear moral reflection, a defender of the irreducible plurality of common-sense moral standards, a powerful opponent of absolute certainty in moral matters, and an insightful critic of consequentialism. And as a great Aristotle scholar, he is able to clarify how practical wisdom informs moral deliberation and to portray, in illuminating detail, both virtue and virtuous action as paradigms of intrinsic value. The essays in this volume examine key aspects of Ross's moral theory: his concept of prima facie duty, his pluralistic theory of the right, his intuitionist epistemology, his pluralistic theory of the good, and his treatments of virtue and of aesthetic value. They will engage anyone interested in Ross's views on these topics or in the topics themselves.