The social and cultural "turn" in language education of recent years has helped move language teaching and curriculum design away from many of the more rigid dogmas of earlier generations, but the issue of the roles of the learners' first language (L1) in language pedagogy and classroom interaction is far from settled. Some follow a strict "exclusive target language" pedagogy, while others "resort to" the use of the L1 for a variety of purposes (see ACTFL 2008). Underlying these competing views is the perspective of the L1 as an impediment to second language learning. Following sociocultural theory and ecological perspectives of language and learning and based on the findings of research on classroom code-switching and code choice, this paper lays out an approach to the language classroom as a multilingual social space in which learners and teacher study, negotiate, and co-construct code choice norms toward the dynamic, creative, and pedagogically effective use of both the target language and the learners' L1(s). Learner use of the L1 for the purpose of grammatical or lexical learning is also considered, and some examples for instruction are offered.