It is argued that (a) social identification is a perception of oneness with a group of persons; (b) social identification stems from the categorization of individuals, the distinctiveness and prestige of the group, the salience of outgroups, and the factors that traditionally are associated with group formation; and (c) social identification leads to activities that are congruent with the identity, support for institutions that embody the identity, stereotypical perceptions of self and others, and outcomes that traditionally are associated with group formation, and it reinforces the antecedents of identification. This perspective is applied to organizational socialization, role conflict, and intergroup relations.