This chapter addresses work in linguistic ethnography which examines language in classrooms in contexts of language diversity. It provides a historical overview of linguistic ethnographic research in language-diverse classrooms, identifying a trend in this area of developing critical understandings of previously taken-for-granted ideas like multilingualism, code-switching and the notion of the native speaker. The concept of heteroglossia is identified as a key contribution across many current studies in the area which has provided a means to rethink these ideas. The chapter goes on to identify three areas of methodological tension characteristic of this kind of research: reflexivity, indexicality and intertextuality. It reviews how these have arisen in a range of studies, and illustrates them with reference to the writer’s own ethnographic research in language-diverse mathematics classrooms in Canada, showing how indexicality and intertextuality are features of both participants’ and researchers’ meaning-making processes. The argument is, thus, that linguistic ethnographic writing is always ‘double-voiced’, and the chapter ends with a reflection on potential future developments of the field, particularly exploring different ways of writing up research that reflect this double-voicedness.