In the article, we consider the impact of adolescence upon the usage of Polish in Polish-German bilinguals raised and living in Germany and demonstrate how adolescence surfaces as a socially based “critical period” in this usage using results from a survey and interviews conducted with 30 teenagers. In the quantitative part of the study, we seek to establish whether adolescents’ age affected the pattern and quantity of their usage of Polish in the media and contacts with age peers, whether the latter two facets of growing up with Polish were interrelated, and which other factors affected peer-relevant activities in Polish. Both age and peer contact turned out to significantly affect the use of the media in Polish, while peer contact in Polish was affected by the parental use of Polish in parent-child communication. The qualitative part presents the context and motivation for using Polish by the youths in peer-relevant activities. We integrate the results with insights provided by child development psychology from the perspective of language socialisation theory and interpret the age-related decline of interest in the Polish media as an effect of a diminishing role of parents and the increasing role of age peers as role models in personal development.