In CLIL contexts, school subjects are taught in an additional language, allowing learners to acquire the target language through meaningful use. This places language teachers in an ambiguous position. What is their role in this context? On the one hand, language teachers are expected to collaborate with subject teacher colleagues; on the other hand, they teach separate language lessons. This double role provides language teachers and their educators with specific challenges in terms of identity and focus. To explore and explain the choices language teachers have, this review examines international research from the last 25 years with a primary focus on secondary schools. As recent discussions argue convincingly that research into CLIL, Content Based Instruction and immersion benefit from convergence and cross-fertilisation, we used a broad range of search terms to identify primary and secondary research. Selected articles were organised into four inquiry areas and analysed thematically: (1) language focus, (2) content focus of learning, (3) language teachers' pedagogical practices, and (4) their collaboration with subject teachers. Based on these themes, we developed a framework for language teachers and their educators in bilingual education designed to help them explore, explain and develop their own identity and focus.