This book critically surveys the leading current approaches to legal and political obligation and examines the most basic moral and metaethical questions underlying those approaches. Contents: Gratitude and Political Obligation; The Logic of Contemporary Consent Theories; "Fair Play" Theories of Obligation; John Finnis on Obligation and the Natural Law; Does Moral Objectivism Matter? Some Preliminary Responses; Polyphony, Dissonance, and Moral Objectivity; Can Debate Over Justice Be Progressive? Conclusion: What Would a Sound Theory of Obligation Look Like?