How have the ideas raised by Firth and Wagner (1997) influenced the construction of second language acquisition (SLA) theories? In this article, we take the position that prior to and since 1997, there was and has been a notable increase in SLA research and theory that prioritizes sociocultural and contextual factors in addition to acknowledging individual agency and multifaceted identities. This article focuses on 4 major influences on a growing body of SLA research: sociocultural theory of mind, situated learning, poststructural theories, and dialogism. We highlight aspects of these perspectives that have been used in SLA theory, and provide examples of research that illustrate the richness and complexity of constructs such as languaging, legitimate peripheral participation, subjectivity, and heteroglossia. These perspectives and constructs address Firth and Wagner's call for a reconceptualization of SLA by offering alternative understandings of language and language learning.