In Natural Law and Natural Rights (1980), John Finnis did for the tradition of natural law theory what his great teacher, H.L.A. Hart, had done 20 years earlier in The Concept of Law for the tradition of legal positivism. He revitalized a classic tradition of thought about law, morality, and their relations by recovering and developing its greatest insights, answering its leading critics, and proposing revisions where thinkers in the tradition had, in his judgment, gone astray. In the course of his project, Finnis made important contributions to contemporary debates about practical reason, justice and the common good, authority, obligation, rights, and the problem of legal injustice. To mark the 25th anniversary of the publication of Professor Finnis's book by Oxford University Press, a distinguished group of legal scholars and philosophers assembles at Princeton University to consider some of the key issues it addressed.