We live in a morally flawed world. Our lives are complicated by what other people do, and by the harms that flow from our social, economic, and political institutions. Our relations as individuals to these collective harms constitute the domain of complicity. This book examines the relationship between collective responsibility and individual guilt. It presents a rigorous philosophical account of the nature of our relations to the social groups in which we participate, and uses that account in a discussion of contemporary moral theory.