Although the Lao People's Democratic Republic has speakers of up to 230 different languages belonging to four ethnolinguistic families, the Lao Government's policy as stated in its Education Law is that Lao is the official language of education at all levels. This creates a challenging situation for teachers in ethnic minority villages throughout the country, where students often begin school with no knowledge of the Lao language. This paper explores the language practices of one teacher in a combined Grade 3 and 4 ethnic minority classroom. It describes how this teacher balances the constraints on him to use Lao as the central language of teaching with his belief in using the students' mother tongue to allow effective teaching and learning to occur. The teacher uses the students' L1 not only in the ways expected of him by national-level policy-makers and planners, or in those often described in the literature on similar contexts, but also in unexpected and creative ways. This has important implications for education policy and planning, particularly in areas such as teacher recruitment, training and deployment, as well as for our understanding of bi and multilingual classroom behaviour.