This article discusses sociolinguistically oriented research on second language acquisition (SLA) in the decade since Firth and Wagner (1997). Over the last 10 years, substantial progress has been made in developing a model of the sociolinguistic processes that inform second language acquisition. This model is supported by empirical evidence on the relationship between social context and second language use and acquisition, which shows that learners' second language (L2) input and processing of L2 input in social settings are socially mediated, that social and linguistic context affect linguistic use, choice, and development, and that learners intentionally assert social identities through their L2 in communicating in social contexts. A strength of sociolinguistically oriented SLA research is its strong focus on linguistic outcomes, tracking the impact of contextual factors in producing those outcomes. Preston (2000, 2002) and Fasold and Preston (2006) provided a central sociolinguistic framework to integrate research on the interaction of social factors and cognitive processes in producing interlanguage, which is a variable linguistic system.