This article discusses a research study that involves five preschool teachers working in linguistically diverse classrooms. It focuses on how these teachers' beliefs regarding language teaching and learning have emerged from their own experiences, and how they affect their understanding of their work. The study draws on the concept of plurilingualism and, to explore what the participants think, know and believe about language learning and language use, employs a dynamic and situated view of teacher cognition--that is, a view which pays particular attention to the specific context of teachers' biographies and their emotional lives. Findings emerging from this research study suggest that, although teachers usually have numerous language learning experiences, their understanding of bilingualism is founded on monolingual assumptions, and, as a result, bilingualism is seen as complete fluency in both languages. In addition, the study proposes an extension of the current understanding of who a language teacher is by including early childhood educators in this conceptualization.