The article considers result-based, attributive, functional, procedural and subjective-symbolic definitions of the phenomenon "ethnic identity" and similar concepts, mechanisms and factors of psychological development of ethnic identity have been identified. Based on the analysis of data from researchers of ethnic identity, the author studied the problems of psychological development.  The main areas of research on ethnic identity are: age boundaries of the stages of formation of ethnic identity, cognitive and affective components of EI, interethnic communication. The study uses a dialectical methodology that allows you to analyze the object of study, ethnic identity, as a holistic phenomenon in its subsequent development. When studying the problem, the method of system-structural analysis was used, the main methodological techniques were the principles of microanalysis and multidimensional. The logical approach contributed to the consistent analysis of the phenomenon of ethnic identity, its mechanisms, factors. The systematic approach contributed to the identification of problems of the psychological development of EI based on research by scientists.