In South Africa, as in many parts of postcolonial Africa, English dominates the political economy and as a result is the medium of instruction chosen by the majority of South African schools, despite the fact that most learners do not have the opportunity to acquire English to the levels necessary for effective engagement with the curriculum. Where teachers and learners share a common home language, there is frequently a gap between language policy and practice, and codeswitching by teachers and learners is a common strategy to achieve a range of social and pedagogical goals. However, in teachers' training the multilingual realities of the classroom have most often been framed in terms of a linguistic problem, with a deficit view of codeswitching. As a result, the potential to use two languages in the classroom in a structured and systematic way to support learning has not been generally recognised or developed. In addition, codeswitching practices are often covert with teachers 'smuggling the vernacular into the classroom' and adopting very different linguistic practices when observed, with serious implications for classroom-based research. This paper explores the conflicts and tensions in classroom codeswitching in the context of macrolevel contestations around language status and rights. (Contains 5 notes and 1 table.)