Studies focused on motivation to learn languages other than English or more than 1 language simultaneously have been gaining attention in recent years. However, there are far fewer than those related to second language (L2) English learning. To fill this gap, this article explores the evolving motivation of 2 Japanese students who spent 1 academic year learning both English and Chinese on a study-abroad program in Taiwan. The data consist of semistructured interviews conducted before and during the program along with motivation graphs drawn by the students. The interviews were transcribed, coded, and categorized. The L2 motivational self system and the concept of the ideal multilingual self are used as frameworks to capture the complex experience of learning multiple languages simultaneously. To capture the dynamic and complex nature of motivation, this article also applies three different timescales (microgenetic, mesogenetic, and ontogenetic) to analyze learners' experiences. The results show how ideal and ought-to second-and third-language selves emerged along with an ideal multilingual self in 1 of the students while abroad. The interviews also revealed multiple learning experiences and struggles in maintaining balance, with both languages competing for limited cognitive resources and study time.

The concept of learner agency has long played a significant role in SLA research. This entry examines the conceptual development of agency mainly from (a) sociocultural and (b) poststructuralist and critical perspectives, both of which influenced the social turn in SLA. Unlike psychological research, which emphasizes learner characteristics, including motivation, with agency regarded as an individual property, agency is viewed here as socially structured and embedded in social contexts. From the sociocultural perspective, agency is never a property of an individual but a relationship constantly co‐constructed and renegotiated with those around the individual and with society. Another important historical development influencing the view of agency in SLA is poststructuralism, alongside the critical theories that followed. Bourdieu's and Giddens's theories, for example, provide a framework for viewing agency in L2 learners by emphasizing the dialectic of social structure and agentive action. Critical theories also supply lenses through which to examine those sociopolitical discourses that produce power differences. Researchers also focus on individuals' agency not only in resisting imposed identities but also in making choices and changing the course of their life. Thus viewed, agency is not a property of free, sovereign individuals but the capacity to create new ways of being through learning an L2. Empirical research into agency in L2 learning and teaching has accumulated since the social turn, reflecting growing interest among SLA researchers in the social and complex nature of agency.