Throughout east and southeast asia multilingual speech communities are the norm rather than the exception. In most countries in the region, nonstandard dialects and ethnic languages survive and even thrive despite the introduction of national languages and their utilization in government, business, and education. Where communicative isolation is not the cause of their survival, the persistence of such regional languages often signals the continuing importance of distinctive infranational identities, operating within (and sometimes across) the boundaries of the modern nation state. Although surely not the only important marker of ethnic or social distinctiveness, language is a particularly rich medium for the expression of social identity. Conversely, the adoption of a new linguistic standard often requires the resolution of what are perceived as competing social identities. In much of developing Asia, therefore, researchers on language history regularly encounter some variant of the same question: what social and historical conditions determine the ways that speakers in multilingual communities resolve problems of language and identity? More specifically, what mix of cultural and political forces ensures that some linguistic varieties persist while others decline or even disappear?