It is outlined the structure of social identity and defines components, the concept of social identity is elaborated and generalized, social identity structure is expanded and supplemented. All social groups to which a person belongs are characterized by membership criteria and boundaries – membership of a religious denomination, nationality, membership in race, ethnicity, also social classes, political ideology, even sexual self-fulfillment performs important functions both on the group and on the interpersonal levels. Thus, a social identity is formed, where society gets an opportunity to include individuals in the system of social relations and relationships, and the individual realizes the basic need for group membership that provides protection, opportunities for self-realization, assessment from others and influence on the group. Identity is also one of the mechanisms of knowledge and understanding of another person. Orientation to another person, for example, significantly increases the rates of social self-determination.