This chapter addresses the role that identity plays in both generating a sense of belonging and in creating division, and presents some of the more important ideas, theories, and findings on self and identity that are relevant to political psychology. The formation of self and identity is particularly linked to the roles are performed, have performed, or aspire to perform. Of particular importance are occupational roles. Social identities are easily aroused and are potent sources of political mobilization especially in cases of identity threat. Henri Tajfel's studies of social identities produced a theory of intergroup relations—social identity theory (SIT). The theory assumes a psychological Marxist view of the world that there first exists society and that “society comprises social categories which stand in power and status relations to one another”. Identity process theory allows one to study the content, process, and context of individual and group identity over time.