The subject of this research is the specifics, forms and functions of interaction in social media groups between the representatives of ethnic communities. The goal consists in determination of the role of social networks in adaptation of ethnocultural communities of St. Petersburg. The research is based on the polling technique for acquisition of information on the cognitive, emotional, and behavioral state of a person. The survey was conducted via distribution of questionnaires among the representatives of ethnic groups. The article also employs the method of systematic scientific observation over the social media groups, topic raised therein, as well as reading and analysis of the comments. The scientific novelty of this work consists in outlining of the nature, trends and development prospects of cross-cultural communications as the channel for ethnocultural interaction. The main conclusions, which touch upon users from various ethnic communities who do not have enough experience in organization of activity of social media groups, demonstrate that it causes the loss of the sense of security, accumulation of prejudices and escalation of interethnic conflicts, as well as preference of the with restricted access, which contributes to lock down of the group and impedes adaptation in the accepting society. Stabilization of situation can be achieved by improvement of the quality of content posted in the social media, as well as level of their administration.