This volume examines the psychological factors, environments, and social factors contributing to identification with extremist identities and ideologies. Incorporating recent findings on interpersonal relationships, emotions, and social identity, the book aims to improve understanding of what makes individuals vulnerable to extremism. It concludes with a discussion of the intricacies of identification with extremist groups, a proposal for de-radicalization, and a call for awareness as a means to resist polarization. Chapters highlight interdisciplinary research into specific concepts and behaviors that can lead to extremism, addressing topics such as:● Homogamy, tribalism and the desire to belong● Shared hatred in strong group identities● The impact of emotional contagion on personal relationships● Dehumanization across political party linesAn in-depth exploration of an increasingly divisive modern issue, The Psychology of Extremism is an essential resource for researchers and students across social psychology, sociology, political psychology, and political science.