As part of the internationalization of higher education, more and more European university courses are being taught in English. Exchanges between universities have grown, and students from different parts of the world now often study together. What does this international environment look like in linguistic terms? Do students and teaching staff speak only the course language English, or are other languages also used, and if so, in what situations and contexts? These questions are discussed on the basis of an ethnographic study of an English-medium university course in Sweden. Extended examples of interaction show that participants adapt their use of languages to place-bound needs and conditions, giving rise to local norms. The national language Swedish holds a special position, as the first language of the majority and the lecturer. The course language English is dominant as a de facto lingua franca, but local social and linguistic needs and conditions leave room for other languages as well. Overall, course participants orient to three competing principles of language use: (a) English as a lingua franca, (b) the speaker's orientation to her or his own language and (c) the special position of Swedish, as the first language of the majority and the lecturer.