This chapter examines postcolonial approaches to International Relations (IR) and their foregrounding of the history and politics of colonialism in the making of the modern world. It first considers the concerns, issues, and preoccupations highlighted by postcolonial theory, along with some of the central debates that have shaped its intellectual terrain, and the normative and political commitments that distinguish it from other related fields such as Marxism and poststructuralism. It then discusses the relevance of postcolonialism to the study of international relations and proposes three different ways of engaging with the insights of postcolonial theory within IR that open up new questions, alternative methodologies, and a range of possibilities for narrating a postcolonial IR. Finally, it analyses international concerns about Iran's nuclear weapons programme from a postcolonial perspective.