This study highlights tensions and challenges experienced by language teachers in CLIL contexts. Using an example from the Netherlands, it explores the pedagogical and collaborative practices of Teachers of English in Bilingual streams (TEBs). The study shows how, using formal and practical theories, pedagogical and collaborative practices were formulated and used to investigate the beliefs and practices of language teachers in bilingual settings. The paper presents the operationalisation of 36 practices for TEBs and reports on an online survey investigating TEBs’ stated beliefs and practices. The findings suggest this set of practices has potential, both as a professional development tool for language teachers in bilingual education settings, and for further research. Results of the online survey revealed that the disciplinary identity of most Dutch TEBs leads to a focus on language, communication, literature, and language arts. TEBs are not necessarily aware of, and do not automatically consider, possibilities for expanding their own pedagogical practices in relation to subject-specific language or supporting and collaborating with their subject teacher colleagues. We suggest that policy guidelines, curricula development and teacher education programmes should pay more attention to the unique position of language teachers in these settings.