The purpose of the work was to study the processes of formation and development of professional identity. The object of this article is professional identity. The subject of the research is the formation and formation of the professional identity of a specialist. The socio-psychological vision of the I-concept of a specialist has been determined. The main components of the development model of the professional identity of an expert in an organization are presented, their content is described. Special attention is paid to the psychological mechanisms of the formation of professional identity: social categorization, identification, alienation. The authors note that the development of professional identity for professionals is better understood as one of the aspects of their socialization in the field of professional activity. In the article, on the basis of a comprehensive theoretical analysis of approaches to the problem of the development of the professional identity of a specialist in an organization that exists in domestic and foreign psychology, a theoretical model of this phenomenon has been built. It can be argued that the formation and development of a positive professional identity is considered the result of the activities of certain psychological mechanisms that are triggered by the basic needs of the individual. The starting point here is the appropriate level of growth of the professional self-consciousness and the “I-concept” of the individual. Professional identity is represented in the “I-image”. Based on a theoretical analysis of the problem of identity formation, the authors identified several factors that influence the development of identity. The main factors are: society and its structure, information environment, elements of collective activity, psycho-physiological characteristics of a person.