This chapter discusses the origins and development of the field of peace studies after World War II, initially in relation to the East-West confrontation and the nuclear arms race. It examines how peace studies responded to the issues of socio-economic disparities and environmental constraints, such as climate change and poverty, that emerged in the 1970s. It also considers the evolution of peace studies as an interdisciplinary and problem-oriented field of study, often in the midst of controversy. In particular, it looks at a number of developments within peace studies, including a major interest in conflict prevention, conflict resolution, and peacekeeping. Finally, the chapter analyses the state of peace studies now and how it is relevant to the new security challenges facing the world.