The psychology of group identification is central to the study of political behavior. Drawing on a chapter in the 2013 Oxford Handbook of Political Psychology, I discuss the conditions under which group identities become politicized, the psychology underlying this process, and the consequences of political identities for political cohesion and engagement. The discussion includes an overview of several distinct theoretical approaches to the study of group-based political cohesion and their competing predictions on the development of political cohesion. I delineate the conditions that generate group-based political cohesion, including strong identities and grievances. I also consider the role played by emotions as a catalyst for group-based political action. Finally, I discuss the conditions under which strong group-based political identities develop. My discussion is informed by findings from diverse research topics including partisanship, patriotism, and ethnic and racial politics.
