The field of security studies has traditionally been a core area of International Relations. In the recent decades it has also become one of the most dynamic and contested areas in the field, conducive to the emergence of versatile and transdisciplinary research agendas. This has unfolded vis-à-vis the traditionally conservative strategic studies which however saw a revival in the post 9/11 era. The course surveys the field of contemporary international security theory and practice from the 1990s until today. It consists of three blocks: (1) revisiting the foundational concepts that have structured the discipline, for example security dilemma and security community; (2) examining the conceptual and sociological underpinnings of innovation in critical security studies; (3) discussion of the most recent articulation of security problematique, for example governing through risk, the role of technology, and the return to the problem of critique.