The paper is oriented toward re-thinking classical categories in migration studies developed in Russian scholarly literature. The author provides definitions adjusted for the needs of empirical sociological research. The theoretical reasoning and empirical findings presented in the paper are based on researches organized and conducted by the International Research Laboratory «Transnationalism and migration pro cesses: comparative and institutional analysis» in 2009-2015. The author proposes his reading of the terms: «migration process» (in its theoretical and empirical interpretations), «emigrant», «immigrant», and «immigrant status». In opposition to the approach commonly practiced in Russian academic literature the paper introduces the division of the migration process into two (not three) stages: the first stage includes actions aimed at receiving the migrant status; the second stage represents actions carried out to lose the migrant status. The article contains the author's classification of immigrants according to their status: labor, education, culture, service, family or forced immigrants. The author also proposes criteria for the operationalization of different types of immigrants according to their formal characteristics and informal practices.