Idioms and phraseological expressions are traditionally considered as the repository of the relevant cultural knowledge of a particular nation; therefore, the study of idioms allows to deepen and expand the knowledge about a national worldview, reflected in the language. The present paper discusses the groups of Russian idioms, the analysis of which contributes to the study of group identity of the native speakers. Russian phraseology is formed in contact with other languages, and cultural information and value meanings contained in idioms reflects the uniqueness of a particular culture. The study considers the interaction and opposition of cultures through the dichotomy “we-they”, which determines the awareness of identity. In order to achieve the goal of the study, a complex methodology is used, which includes the methods of linguistic and cultural analysis. The study examines 1) the borrowed phraseological expressions, which changed their meaning; 2) native phraseological expressions which have received additional connotation or meaning; 3) phraseological expressions containing anthroponyms, toponyms and ethnonyms. As a result, it is concluded that the meaning of borrowed idioms can be transformed, thus acquiring national specificity due to changes in the awareness of the cultural identity of the people.