The present article deals with language choice as communicative strategies in the language learning environment of an English-medium content and language integrated learning (CLIL) workshop at an auto mechanics class in a Swedish upper secondary school. The article presents the organisation and functions of language alternations (LAs) which are learner-initiated and teacher-impelled [Üstünel, E. and P. Seedhouse. 2005. "Why that, in that language, right now? Code-switching and pedagogical focus." "International Journal of Applied Linguistics" 15: 302-25]. The data are drawn from ethnography combined with audio and video recordings of learners in a beginner's level workshop and in an English as a foreign language classroom. A close analysis of languages chosen locally is combined with ethnographic knowledge of the broader social context of the alternations, and in both theory and method, the article combines the research fields of sociolinguistics and ethnography. The study demonstrates that LA in vocational CLIL classrooms is orderly, it is related to the evolution of communicative strategies and it is in accordance with and reproduces local language norms. Thus, English-medium education does not by definition mean that English is the only language employed. On the contrary, students play around with language and use different strategies, including the use of another language, to make themselves understood.