This book develops a general theory of law, inclusive legal positivism, which seeks to remain within the tradition represented by authors such as Austin, Hart, MacCormick, and Raz, while sharing some of the virtues of both classical and modern theories of natural law, as represented by authors such as Aquinas, Fuller, Finnis, and Dworkin. Its central theoretical questions are: Does the existence or content of positive law ever depend on moral considerations? If so, is this fact consistent with legal positivism? The author shows how inclusive positivism allows one to answer yes to both of these questions. In addition to articulating and defending his own version of legal positivism, which is a refinement and development of the views of H.L.A. Hart as expressed in his classic book The Concept of Law, the author clarifies the terms of current jurisprudential debates about the nature of law. These debates are often clouded by failures to appreciate that different theorists are offering differing kinds of theories and attempting to answer different questions. There is also a failure, principally on the part of Ronald Dworkin, to characterize opposing theories correctly. The clarity of Waluchow's work will help to remove the confusion which has hitherto marred some jurisprudential debate, particularly about Dworkin's work.