National and ethnic enclaves constitute one of the forms of "parallel spaces" materialization (In the entire palette of inherent properties) and, therefore, it is legitimate to qualify them as a unique practice of refraction of the concept of multiculturalism. Historical experience has shown that the presumption of mutual desire for integration based on the recognition of the concept of multiculturalism as a guiding principle of relations (primarily in relation to European states and migrant groups within their borders) did not justify itself due to insufficient consideration of the entire scope of influencing factors (risks). On this basis, the author emphasizes the importance of applying an approach the structure of which includes differentiated complex methodological formulas (political and legal, socio-economic, national-cultural) that encourage harmonization of "foreign" authentic cultures (including religious practices, behavioural patterns in the framework of social environments) with a dominant and historically determined culture of the host community with the recognition of the primacy of its culture (including a heterogeneous nature).Enclaves are viewed as a spatial-geographical and socio-institutional phenomenon. The spatial and geographical component reflects the infrastructure landscape of the enclave, including the inherent economic, production, and environmental features in certain geographical coordinates (at the location). A socio-institutional variable characterizes a community that has appeared and functions by virtue of and within certain groups of co-identity parameters (national, religious, linguistic, legal (usually legal), etc.), emphasizes its inherent connections (internal and external). Under national-ethnic enclaves it is proposed to understand separate quasi-territorial formations, where, due to objectively forced conditions, national minorities (mainly migrant groups) live compactly (permanently or temporarily), adhering to an authentic way of life that differs from the generally accepted way (mainstream) in the host society. The paper highlights the characteristic imperative and optional features of enclaves, emphasizes the heterogeneous configuration of the social structure of enclaves, investigates the reasons for the formation and functions of ethno-national enclaves, identifies the similarities and differences between enclaves and ghettos and ethno-burbes.