The idea of language teachers as active agents both inside and outside the classroom has long been a guiding concept in applied linguistics and education. At its core, teacher agency aims to describe teachers' efforts to make choices within a host of contexts: in establishing and maintaining relationships with learners and colleagues, in engaging with new curricular requirements and assessment practices, in innovative learning, in participating in ongoing professional development opportunities and teacher workplace learning initiatives, in adapting themselves to the diverse requirements of their working contexts, and so on. Lack of agency in relation to such areas as pedagogical tasks, workplace relationships, innovation and student learning has long been recognised as a problem for teachers. Yet, until recently, the concept of teacher agency has received relatively little attention in applied linguistics research, with teachers being seen more in relation to learners than as 'agents in their own right' (Kalaja et al., 2015: 14).

Recent and current approaches to teacher agency have also included a focus on emotion and identity together with such notions as identity-agency (Ruohotie-Lyhty & Moate, 2016) and life-course agency (Ruohotie-Lyhty & Moate, 2015). New lines of enquiry have emerged in Ng and Boucher-Yip's (2016) edited collection on teacher agency and policy responses in English language teaching, and in recent articles on teacher agency in relation to norms and varieties of English (Hamid et al., 2014), to the interactional dynamics of bilingual classrooms (Palmer & Martínez, 2013), and to language planning and policy in Vietnam (Van Huy et al., 2016). Studies such as these reveal the wide currency of the construct of teacher agency together with the studies reviewed later in this chapter, which are concerned with the influence of experiences outside the classroom (Feryok, 2012), identity negotiations and teacher agency (Kayi-Aydar, 2015), the emergence of agency through CALL practice (Kitade, 2015), and teacher agency in narrative accounts of classroom conflict (White, 2016).