Identity and second language acquisition (SLA) is best understood with reference to changing conceptions of the individual, language, and learning in the field of applied linguistics. These changes are indexical of a shift in the field from a predominantly psycholinguistic approach to SLA to include a greater focus on sociological and anthropological dimensions of language learning, particularly with reference to sociocultural, poststructural, and critical theory. This entry examines the work of scholars who are centrally concerned with the relationship between the language learner and the larger social world, and the way in which power is implicated in SLA. Key directions in identity research are addressed, including identity and investment, social categories, and digitally mediated language learning. It is argued that social processes marked by inequities of gender, race, class, ethnicity, and sexual orientation may serve to position learners in ways that silence and exclude. At the same time, however, learners may resist marginalization through both covert and overt acts of resistance. Of central interest to researchers of second language identity is that the very articulation of power, identity, and resistance is expressed in and through language.