Over the last twenty years, sociolinguistic research on multilingualism has been transformed. Two processes have been at work: first, an epistemological shift to a critical ethnographic approach, which has contributed to a larger turn toward post-structuralist perspectives on social life. Second, the effects of globalization--transnational population flows, new communication technologies, transformations in the political and economic landscape--have sparked increasing concern about the implications of these changes for our understanding of the relationship between language and society. A new sociolinguistics of multilingualism is being forged: one that takes account of the new communicative order, while retaining a central concern with the processes in the construction of social difference. The contributors to this volume have been at the forefront of these epistemological shifts. They write here about the conceptual and methodological challenges posed by these shifts, and the profound changes that we are witnessing in the late modern era.