This Element provides a systematic defense of moral contractarianism as a distinct approach to the social contract. It elucidates, in comparison to moral conventionalism and moral contractualism, the distinct features of moral contractarianism, its scope, and conceptual and practical challenges that concern the relationship between morality and self-interest, the problems of assurance and compliance, rule-following, counterfactualism, and the nexus between morals and politics. It argues that, if appropriately conceived, moral contractarianism is conceptually coherent, empirically sound, and practically relevant, and has much to offer to contemporary moral philosophy.