Social Identity Theory: Group Identity, Intergroup Bias, and the Psychology of Collective Belonging
Social identity theory explains how individuals derive part of their sense of self from membership in social groups. Developed by Henri Tajfel and later expanded with John Turner, it remains one of the most influential frameworks in modern social psychology because it shows that people do not understand themselves only as isolated individuals. They also experience themselves as members of groups such as nations, professions, political communities, religions, and cultural collectivities, and those memberships shape perception, loyalty, comparison, and conflict. The theory’s enduring importance lies in demonstrating that intergroup bias does not require deep historical hatred, direct material competition, or pathological personalities alone. Group membership itself can become a powerful source of meaning and evaluation. Once people categorize themselves and others into ingroups and outgroups, those boundaries begin to structure trust, favoritism, dignity, and status. For that reason, social identity theory is indispensable for understanding prejudice, polarization, organizational rivalry, nationalism, and the broader social processes through which identity becomes a source of both solidarity and division.









