This chapter introduces feminist perspectives on international relations. It provides a typology of feminist International Relations (IR) theories, outlining their major tenets with illustrations from specific authors. Feminist theories of IR use gender as a socially constructed category of analysis when they analyse foreign policy, international political economy, and international security. This chapter focuses on feminist perspectives on international security. Feminist security research takes two major forms: theoretical reformulation and empirical evaluation. This chapter chronicles developments in feminist reanalyses and reformulations of security theory. It illustrates feminist security theory by analysing the case of United Nations Security Council sanctions on Iraq following the First Gulf War. It concludes by discussing the contributions that feminist IR can make to the discipline of IR, specifically, and to the practice of international politics, more generally.