Adolescence is the time of multiple changes in one’s life. These changes occur particularly in the social domain: teenagers adopt roles of an adult. This transition leads to changes in the family interaction and particularly also in relationships with grandparents. A solid body of research on teenagers was focused on parent-child relationships while few addressed the influence of grandparents on this process of transition. Authors (Letiecq, Bailey, & Kurtz, 2008) argue that grandparents provide both material support and transfer of cultural heritage, and maintain family educational level and values. We hypothesized that the association of personality traits with social adaptation can be mediated by the relationships with grandparents. Methods used were (1) the questionnaire “Interaction parent-child” (Markovskaya), (2) a method of diagnostics of personality, social, and psychological adaptation (Rogers, Dymond, Osnicky), and (3) the 16PF personality test (Cattell). Subjects were 99 teenagers aged 14 – 17 (51% female). Results showed that the absence of the grandmother was negatively associated with both overall adaptation score (t=-2,31; р=0,025) and escapism level (t=-2,61; р=0,012). Having a grandmother around was associated with internal locus of control (t=2,25; р=0,029), emotional stability (t=2,02; p=0,048), expressiveness (t=3,22; p=0,002), readiness for risk (t=2,87; p=0,006). Comparative analysis revealed that teenagers who were interacting with their grandmothers were more conservative (t=-2,51; p=0,02) and restrained (t=-3,06; p=0,003). Meanwhile teenagers interacting 122 with the grandfather showed higher scores on liveliness (t=3,22; p=0,002). Thus, we can suggest that grandmothers transfer their life experiences and wisdom to their grandchildren, providing teenagers with a better understanding of social roles, and help to find adaptive forms of behavior. We can also hypothesize that family structure that includes grandparents provides a better background for the development of social networks by teenagers. This project was supported by RFBR grant 19-013-00861.