This book examines the importance of rules for many of the world’s great moral traditions. Ethical systems characterised by detailed rules – Islamic sharia and Christian casuistry are notable examples – have often been dismissed as empty formalism or as the instrument of social control. This book demonstrates, on the contrary, that rules often enable, rather than hinder, personal ethical life. Here anthropologists and historians explore cases of rule-oriented ethics and their dynamics across a wide range of historical and contemporary moral traditions. Examples of pre-modern Hindu ethics, codes of civility from early modern England and medieval Christian casuistry demonstrate how rules can form an essential element of what Michel Foucault called ‘the care of the self’. Studies of Roman exemplary ethics, early modern Christian theology and the calculation of sin and merit in contemporary Muslim Palestine highlight the challenges posed by the coexistence of moral rules with other moral forms, not least those of virtue ethics. Finally, explorations of medieval and modern Islamic sharia, Christian moral theology and Jewish halakhah all highlight how such traditions develop complex meta-rules – rules about rules – for managing the tensions and dilemmas that the use of rules can entail. Together, these case studies and the theoretical framework proposed in the book’s Introduction offer a more nuanced, cross-cultural appreciation of the role of rules in moral life than those currently prevalent in both the anthropology of ethics and the history of morality.