Not only since the end of the cold war, the organization of violence and security on the international level – a state-centric system, based on armed military and police forces, and revolving around balance of power – has been challenged. Arguably the classical order has been amended or even supplanted, by multiple other forms of organized violent actors. This module is an introduction to the theoretical and empirical security studies literature on violent non-state actors, such as private security companies, warlords, terrorist and international criminal organizations. In detail, this module investigates under what circumstances non-state actors resort to violence, explores the logic of their behaviour, and discusses potential government measures to counter such violence. Moreover, the course will grapple with theoretical question of how IR-theory can inform and facilitate research on non-state actors. Although the module is mainly thematically-driven, the course will also review several current cases studies (e.g. Afghanistan, Iraq, 9/11) to provide students with a better understanding of the shifting patterns of conflict, violence and security in the international system.