Code switching involves the interplay of two languages and as well as serving linguistic functions, it has social and psychological implications. In the context of English language teaching, these psychological implications reveal themselves as teachers' thought processes. While the nature of code switching in language classrooms has been widely studied, as yet little if any attention has been paid to the relationship between such switching and the beliefs of the teachers involved. This study is designed to respond this gap in existing research. Five student teachers participated in the studies who were undertaking their teaching practicum at a private school in Turkey, aiming to investigate their thinking in relation to code switching in their classrooms by using the analysis of classroom interactions, individual interviews and stimulated recall interviews. The first step of the research involved video recording the lessons taught by the five student teachers within the framework of their university Teaching Practice course. This was followed by individual interviews with the student teachers focusing on their views of code switching during their teaching experience and their general views about language teaching. The last stage involved stimulated recall interviews with the student teachers based on selected extracts from their lessons chosen after an analysis of spoken interaction in their classes. The data were then analysed using thematic analysis. The findings revealed that code switching is more than merely a linguistic matter; it is also indicative of a number of other dimensions including how teachers define themselves professionally, teacher beliefs, teacher identity, affective factors influencing teachers and their relationships with supervisors. This study suggests that code switching could usefully be included as a topic in teacher education programmes and in supervisor/mentor training.