This article reviews two sets of research studies from outside of mathematics education to consider how they may be relevant to the study of bilingual mathematics learners using two languages. The first set of studies is psycholinguistics experiments comparing monolinguals and bilinguals using two languages during arithmetic computation (language switching). The second set of studies is sociolinguistic research on young bilinguals using two languages during conversations (code switching). I use an example of a mathematical discussion between bilingual students to illustrate how sociolinguistics can inform analyses of bilingual mathematical conversations.