The paper deals with the phenomenon of ethnicity, ethnic identity, and the specifics of its formation. The article reveals the complex polyparadigmatic nature of the interpretation of the concept of ethnos, which assumes an incomplete confrontation of positions in the framework of such areas as constructivism and primordialism. The author reveals the aggravation of the ethnic issue at the present stage of its development. The actualization of the ethnic Renaissance is associated with the following reasons: the protective reaction of local cultures in the period of global transformations; intensification of the migration process and the desire of migrants for self-categorization; external aggressive factors initiating attention to the issues of ethnicity. The article features the phenomenon of ethnocentrism with its positive and negative aspects. The author 1) puts emphasis on the importance and the dialectical character of auto- and heterostereotypes in the formation of positive ethno-cultural identity, 2) draws attention to the manifestation of ethnocentrism in various forms of hyperpositive and negative ethnic self-identification, 3) highlights the danger of ethnic domineering, which may escalate conflict situations. According to the author, ethno-fanaticism is a manifestation of ethno-cultural neurosis, which can be used as a dangerous tool in socio-political construction and management. The research reveals the dual nature of the phenomenon of ethnonationalism. The author emphasizes that it is necessary to distinguish between cultural and political nationalism since they perform various functions and manifest themselves at opposite levels, from solidarity and patriotism to ethnic terrorism.