This paper provides insights into online language practices among bilingual teenagers who speak and learn a lesser-used language. Regarding language diversity, the internet is seen to pose both challenges to and opportunities for smaller languages. Focusing on German-Upper Sorbian adolescents, this study enquires to what extent new media and technologies facilitate Sorbian-language maintenance and learning, and what influences language choice (German, Sorbian or other) in online environments. Via questionnaire and group discussion methods, it is revealed that German dominates the online activities of participants (n = 164). However, Sorbian assumes relatively stronger roles in online activities for school/homework, as well as chat, social media and internet telephoning. Although German dominates these users' online environments, the educational and interactive roles that Sorbian plays are a relatively good indicator of biliteracy activities. Yet these two roles do not seem to converge. Students claim to use technologies for the 'correct' use of Sorbian in the formal domain of education, whereas biliteracy in social media can also refer to ways in which German and Sorbian (and increasingly English) are mixed in informal, non-standard and creative ways. Language choice online largely reflects offline behaviours, yet new issues also emerge, such as available software in the minority language.