The percentage of pupils fluent in both Swedish and Finnish in Swedish-speaking schools in Finland has grown and now includes a third of all pupils. This article focuses on the linguistic classroom discourse in a Swedish-speaking school in a strongly Finnish-dominated area. The purpose is to increase the understanding of how linguistic norms are maintained, and what these norms imply for the participation of bilingual pupils in classroom interaction. Videotaped lessons were analyzed by means of conversation analysis focusing on the interaction between the teacher and the bilingual pupils as well as on language-related sequences. The results show that the bilingual pupils cannot be regarded as victims of a language policy governed from above, but that they actively contribute to the construction and maintenance of a monolingual norm in the classroom. When using Finnish, they at the same time point at the “other-languageness” of the code-switched words. Monolingualism as a norm means a limitation restraining the pupils with gaps in their Swedish from participating with full competence in the classroom conversation. Between pupils, occasional Finnish words are used in an unproblematic manner. Code-switching in these cases works as a means to keep one's position on the conversational floor. By violating the monolingual norm, pupils can lodge a protest against the agenda of the teacher.