This handbook offers readers an overview, including policy implications, of research into the psychology of radicalization, terrorism, and response to terrorism. The Editors, themselves leading terrorism scholars, introduce psychological theories of terrorist behavior, examining both risk and protective factors, the role of leadership, environments that can be identified as radicalization breeding grounds, as well as the way that emotions impact radicalization and terrorism. The book not only looks at recent directions of radicalization, and how we can assess or predict their potential for terrorist violence, but also at the latest programs of deradicalization and the psychological tools they employ.