Integrating research on multilingualism and computer-mediated communication, this paper proposes the term ‘networked multilingualism’ and presents findings from a case study to explore its implications for the theorising of multilingualism. Networked multilingualism is a cover term for multilingual practices that are shaped by two interrelated processes: being networked, i.e. digitally connected to other individuals and groups, and being in the network, i.e. embedded in the global mediascape of the web. It encompasses everything language users do with the entire range of linguistic resources within three sets of constraints: mediation of written language by digital technologies, access to network resources, and orientation to networked audiences. The empirical part of the paper discusses the Facebook language practices of a small group of Greek-background secondary school students in a German city. Data collection follows an online ethnography approach, which combines systematic observation of online activities, collection and linguistic analysis of screen data, and data elicited through direct contact with users. Focusing on four weeks of discourse on profile walls, the analysis examines the participants’ linguistic repertoires, their language choices for genres of self-presentation and dialogic exchange, and the performance of multilingual talk online. The findings suggest that the students’ networked multilingual practices are individualised, genre-shaped, and based on wide and stratified repertoires.