The proposed study will analyze how teenagers adapt their informal online writing to their conversation partner, and by which social and contextual factors this process of accommodation is influenced. Since linguistic accommodation remains largely un(der)explored for social media writing, the project fills a gap. It will investigate the impact of multiple aspects of adolescents' socio-demographic profile and their interaction on a wide range of linguistic and pragmatic features. We will examine whether divergent patterns of linguistic adjustment can be observed for teenagers with distinct socio-demographic profiles, and which language features appear to be most or least affected. A major distinction will be made between analyses of robust intergroup accommodation and in-depth diachronic analyses of accommodation between particular individuals. This unique design might lead to challenging sociolinguistic findings with respect to the profile of (non-)accommodators. While it will primarily increase our understanding of the social, linguistic and pragmatic parameters that govern accommodative language behavior, it may in the end also open up a unique perspective on language change. Moreover, on a more general, theoretical level, this project aims to accurately delimit the concept of accommodation, in order to answer the fundamental question of whether we can unambiguously discriminate between true accommodation and other instances of linguistic adaptation.