The article notes that the theoretical and experimental research is one of the possible approaches to the systematic study of the psychological phenomenon of ethno-cultural marginality. The main parameters of the analysis of the phenomenon of ethno-cultural marginality were determined. The analysis of researches has shown that semantic loading of the term "marginality" in most cases is reduced, basically, to its negative maintenance and to a context of a problem of "duality of ethnic consciousness". In ethnosocial studies, the concept of "ethno-cultural marginality" expresses, first of all, the discrepancy between the" ethnicity "of a person and certain ideas about the" normative identity " of a particular person or ethnic group. Accordingly, the existing differences in the understanding of "ethnic identity" cause multivariate interpretations of ethno-cultural marginality. The experimental study of the phenomenon of ethno-cultural marginality showed that ethno-cultural marginals are characterized by the problem of ethnic self-determination.