THE PUBLICATION OF THE DOUGLAS FIR Group's (DFG, 2016) article reminded me of recurring paradigm debates in our field over the last 3 decades (e.g., Firth & Wagner, 1997, 2007; Zuengler & Miller, 2006). The essence of these debates revolves around the critical question of whether or not we should attribute primacy to the individual brain or the social world when exploring language learners’ learning processes. By their very nature, these paradigm debates are serious and have significant implications for research and practice, as they help to define what counts as legitimate second language acquisition (SLA) research. My colleagues often call the paradigms in these debates “bubbles,” which both envelop us and enable our intellectual pursuits. We pursue our intellectual interests through the bubble surrounding us, which often deflects reality into constructions. As a language teacher educator, I believe that the constructions in these paradigms should be put to the test by language learners and teachers in practice, so that we may recognize whether they constitute sensible solutions or responses to the challenges we face in an increasingly diverse world. For this reason, I believe that the DFG's proposal has significant implications for language teacher education, since it recommends “practical, innovative, and sustainable solutions that are responsive to the challenges of language teaching and learning in a multilingual world” (p. 20). In this commentary, I will first explain how my intellectual efforts so far have been related to the basic tenets in the DFG framework. Then I discuss how the framework, enriched by the collection of papers in this volume, presents both challenges and learning opportunities for language teachers. I conclude that transforming these challenges into learning opportunities will necessitate substantial reforms in many language teacher education programs. I welcome the publication of the DFG article on a transdisciplinary framework for SLA in a multilingual world because such a framework fits closely with the intellectual journey I myself have undertaken since my doctoral studies some years ago. Starting my academic career as a language learning strategy researcher, I have been interested not so much in strategies in and of themselves but in understanding why language learners adopt particular strategies in a given context (e.g., Gao, 2010). In that sense, my research on language learning strategies has always been transdisciplinary, drawing on sociocultural perspectives on language learning and debates about agency and structure in the social sciences (Layder, 1990) to inform my interpretation of learners’ strategic language learning narratives. In my research I portray language learners’ strategy use not only as a cognitive choice, but also as a choice facilitated or constrained by contextual conditions (e.g., Gao, 2007, 2010). To some extent, then, my multifaceted approach to language learners’ strategy use echoes the theoretical considerations captured by the DFG framework while applying them to a particular area of inquiry. At the same time, it is fair to say that, although the publication of my doctoral thesis as a research monograph was positively reviewed by some researchers in the field, overall, its ideas have not received much attention in the academic community. In part, this may be due to the fact that language learning strategy researchers face an almost insurmountable challenge posed by those advocating the replacement of the construct with self-regulated learning capacity (e.g., Rose et al., 2018; Tseng, Dörnyei, & Schmitt, 2006). But much larger issues are at play: Socializing with SLA researchers at major applied linguistics conferences frequently leaves me with the impression that my approach, at best, is alternative to more mainstream and dominant approaches, perhaps even marginal. Fortunately, after I became a language teacher educator that discomfort has gradually subsided—most likely because my new role challenged me to commit myself to conducting research that spoke more directly to the concerns of language teachers. Immersing myself in research with explicit pedagogical implications, I realized that language learning and teaching take place in a complex milieu, mediated by a variety of conditions and relationships within and beyond the confines of classroom walls. It is well known that many of these are beyond the teachers’ control. And yet, having been socialized into a professional culture that has long assigned responsibility for learner success to them, they are eager to find ‘best practices’ that would assure that success. With regard to motivation, for example, language teachers often look to teacher educators for ‘magic’ ways through which they might ‘trigger’ a redoubling of efforts on the part of their learners. However, even though motivation is indeed a key factor in explaining variations in learners’ achievements (Boo, Dörnyei, & Ryan, 2015), motivation is an extraordinarily multifaceted phenomenon, arising from the interaction between individual language learners’ beliefs and attitudes, input and influences from social agents (e.g., peers, parents, teachers) within the different social groups (or communities) to which they belong, as well as ideological discourses about learning at the macro-contextual level (Gao, 2010; Harvey, 2017; Lanvers, 2018). As I stated at the outset, discussions of paradigm shifts are hardly new in the language studies field. Even so, I welcome the DFG framework with its 10 research themes as a key intellectual resource underlying transdisciplinary, innovative research that can generate critical insights for language learners and teachers to improve their well-being. That positive assessment may, in part, stem from the fact that the DFG framework directly connects my work to some of the central debates in our field, rather than relegating it to the periphery. Far more important, however, is my belief that the DFG framework can serve as a pedagogical resource for language teachers thatenables them to position their teaching within the big picture of learning and teaching and, thereby, encourage them to re-commit themselves to supporting their own language learners by any means whatsoever. It also provides a guide for language teacher educators to help language teachers maneuver strategically in pursuit of professional development. In other words, the framework not only presents a research resource map that underpins holistic inquiries into “language learning and teaching” by “taking into account forces beyond individual learners” (DFG, 2016, p. 20); it also maps out the complexity of the learning and teaching that language teacher educators need to impart to language teachers for their professional development. The collection of studies in this issue can be approached from different perspectives, but as a language teacher educator I believe that they highlight at least four challenges for teacher educators in the preparation of language teachers: (a) the deficit discourses about language learners associated with the monolingualism bias in SLA research (Ortega, 2019, this issue), (b) integrating a broadened theorization of cognition in teaching (Ellis, 2019, this issue), (c) taking a usage-based approach to linguistics to inform pedagogical decisions (Hall, 2019, this issue; LaScotte & Tarone, 2019, this issue), and (d) becoming fully empowered agents in the pedagogical process (Larsen–Freeman, 2019, this issue). The first three challenges raise critical questions about why language teachers teach, how language learners learn (and hence how language can be taught), and what is to be taught. Properly addressed, language teacher education programs will present rich, meaningful learning opportunities that are essential to language teachers’ professional development as they learn the task of teaching in a multilingual world. The last challenge goes to the heart of language teachers’ professional development as the DFG framework envisions it. One of the most significant challenges in my career as a language teacher educator has been to help language teachers recognize the deleterious consequences of the reigning monolingual prejudice in SLA research, which has led to the enshrining of native speaker norms as the privileged target of all language learning and teaching. Perhaps such a goal is achievable by a select few learners in highly unusual circumstances and, most likely, even then at considerable costs (e.g., financial and social). But its dominance (for an example in the Chinese context, see Wang, 2015) based on a fundamental bias in favor of a small group of privileged language learners is extraordinarily difficult to address—much less resist—for researchers, teacher educators, teachers, and learners alike. Research conducted in Western,educated, industrialized, rich, and democratic contexts (“WEIRD” research) prides itself on producing complex and elaborate justifications and procedures that are intended to inform language teachers’ pedagogical decisions. But teachers in other contexts may find their arguments as well as their educational recommendations both unpersuasive and irrelevant, not least because of the glaring gap between the biases of such academic research and their own pedagogical reality. Even more important, by reducing the complex reality of multilingual competence to dichotomies like native and nonnative, monolingual and bilingual, they inflict additional, deeply disturbing insecurities beyond those that are already part of the complex endeavor of language learning and language use—and do so for both the multilingual learners as well as their teachers (cf. Ortega, 2019, this issue). Over the years I have found that it is ineffective to address the impact of deficit discourses on language teachers simply by changing the ways in which we describe language learners and learning, for example by changing “language barrier” to “language difference.” Without a fundamental shift in how teachers can understand the verynature of their professional work and, accordingly, the nature of their commitments and responsibilities, well-intentioned replacive words with positive meanings all too soon assume the same negative connotations that have pervaded the earlier deficit discourses. As suggested by Ortega, only when language teacher education programs incorporate social justice and equity into their core missions can we begin to tackle this deep-seated bias. That means, language teacher educators need more research that pertains to a myriad of aspects of language use and language learning as these describe the vast majority of language learners who do not belong to the over-studied multilingual elites. One obvious starting point for such research might be the multilingual teachers themselves who, around the globe, bring particular strengths to their work and—as we hear over and over again from their students—are role models that inspire and motivate, often for a lifetime. For years, language teachers have been urged to provide “authentic language” through “natural learning” (e.g., Widdowson, 1998, p. 705; original italic). However, language teachers “need to make language and language learning a reality for learners” (Widdowson, 1998, p. 715), a demand that draws attention to theorization about language cognition in context. By focusing on language learning within micro and macro contexts, the DFG framework presents a theorization of cognition as socially distributed and as taking place within a human body that connects cognition and the world. Individual learners’ language cognition is dependent on context and is enacted through learner action upon the context (e.g., Atkinson et al., 2018; Zuengler & Miller, 2006). This recognition underpins the growth of a variety of theories of language learning, including sociocultural perspectives (e.g., Lantolf, 2009), complex dynamic system theory (e.g., Larsen–Freeman, 1997), and usage-based approaches to language development (e.g., Ellis & Larsen–Freeman, 2006). With regard to language pedagogy development, these perspectives on language learning imply the necessity for language teachers to draw on what language learners are exposed to outside the classroom in order to develop meaningful pedagogical activities in the classroom, which will prepare them well for the task of using the language in real life. In other words, language teachers need to consider “frequent and rich participation in the second-language life worlds into which the learner ‘bricolages’ his or her way” (Ellis, 2019, this issue, p. 52) as both the starting and end points for language teaching activities within the classroom toward language learning and use. Considering the fact that many language learners (particularly those in low-resource situations) have few opportunities to use the language outside the classroom, it remains a critical task for language teachers to develop, create, and sustain learners’ meaningful access to these “second-language life worlds,” not least because doing so may help reduce inequity among language learners in the learning process. However, most language teacher education programs that I am aware of have yet to develop language teachers’ capacity to promote language use beyond the classroom in low-resource teaching contexts. The socially distributed nature of cognition, as outlined by Ellis, draws attention to the significance of the gaps that different language learners may experience in their exposure to the target language and their ultimate language learning achievement. This requires language teacher educators and language teachers to work out ways to address these gaps and minimize the impact of social inequity on language learners’ learning progress. The usage-based understanding of language, as one fundamental pillar of the DFG framework, presents another significant challenge for language teachers and language teacher educators. For years, we have engaged in debating form versus meaning in language teaching. But as Hall (2019, this issue) argues, a usage-based understanding of language necessitates fundamental shifts in conceptualizing a number of key constructs in language teaching, such as replacing “language competence” with “language repertoire,” and “language expertise” as well as “grammar” with “semiotic resources” and “semioticregisters.” Drawing on interactional linguistics, Hall (2019, this issue) presents grammatical practices as “shaped by actional turns…within interactional sequences” (p. 84), and conversation analysis as seeking to uncover “the publically witnessable universal infrastructure, as exhibited in the methods used by members to achieve social order” (p. 86). In light of such an understanding of language, many language teacher education programs will need to examine critically how they theorize language so that the programs can prepare language teachers with “theories of language that foreground meaning rather than structure” (Lantolf, 2009, p. 274). Among the consequences of such an approach will be that language teachers should encourage learners to deploy lexical and grammatical resources from different registers to establish their own voices or enact those of others, as revealed in LaScotte and Tarone's (2019, this issue) study on language learners’ differential development of complexity, accuracy, and fluency in different ‘voice’ environments. In sum, the articles in this collection present a coherent transdisciplinary framework, which entails significant challenges for language teachers and language teacher educators in the pursuit of a more equitable world through language education. To overcome these challenges, we must recognize language teachers as reflexive and reflective agents, who are able to critically evaluate knowledge resources and uncertain conditions before making pedagogical decisions that advance their professional ideals. That means, we need to understand how teacher agency underlies professional development. Larsen–Freeman (2019, this issue) enriches the Douglas Fir Group framework with a temporal element with regard to learner agency. That enables her to capture the dynamism of the framework as compared with the earlier, more flat and two-dimensional portrayal. Language teachers’ professional development, too, can be seen as a dynamic process emerging from interaction between teacher agency and contextual structures as outlined in the framework. While the DFG framework can be used as a resource to help language teachers appreciate the complexity and dynamism of language learning and teaching, it is also a roadmap for them to see how their professional learning might unfold in the specific contexts where they learn and teach. Depending on where we locate agency in the framework, agency can be theorized as capacity or phenomenon/doing (Priestley et al., 2012). If we place agency with “individuals engaging with others” in the framework, we may consider it as “the socio-culturally mediated capacity to act purposefully and reflectively on [one's] world” (Rogers & Wetzel, 2013, p. 63; see also Ahearn, 2001). Such a consideration acknowledges social contributions to the development and exercise of agency, but it may not be well suited to helping us to “identify agentic actions,” as agency and structure are mutually constitutive in this conceptualization (Hitlin & Elder, 2007, p. 173). For this reason, it is, perhaps, more appropriate to regard language teachers’ agency as phenomenon/doing, or something “achieved and not as merely … a capacity or possession of the individual” (Priestley et al., 2012, p. 197), a position that confirms the significance of adding Larsen–Freeman's (2019, this issue) temporal element to the DFG framework. Inevitably, its integration into language teacher education programs compels language teachers to critically examine and change their beliefs about language, learning, and teaching. The traditional emphasis on language structure in language teacher education programs does not help language teachers to prepare learners for using language structures as semiotic resources to create meanings and assert themselves. Rather, it creates an irresistibly tempting—though false—sense of security and authority for language teachers. Without the aid of deterministic language rules and orderly language development paths as these have been suggested by many SLA studies, language teachers will be called to “confront, resist and work out pedagogical conflicts” as well as “overcome unequal power relations” in professional practice, in which “teacher agency plays a key role” (Tao & Gao, 2017, p. 347). That means that we must recognize their “rights” to control and their “responsibility” to sustain their professional development for the task of language teaching, positions that are reflected in the DFG framework (see also, Johnson, 2006, p. 250). Since language teachers learn and teach in a broader milieu of preset conditions and prior experiences in particular contexts, their agentic responses may be manifest in the forms of compliance, resistance, and negotiation over the course of time. Language teacher educators and researchers need to critically examine and endeavor to change structural elements (e.g., conceptions of language learning and teaching endorsed by the powerful) that might have constrained language teachers’ learning and the application of new pedagogical ideas in a given teaching context. In other words, language teacher educators not only need to provide knowledge and experience to enable transformation among language teachers; they should also explore ways to create and sustain the contextual conditions that are conducive to changes in their learning and professional practice. Publication of the DFG (2016) article may be regarded as a in the development of what counts as SLA research. The framework can be seen as a point for a group of SLA researchers who on related to language teaching In my it also language teacher educators like me to how the framework can be used to inform the development of language teacher education programs by why we teach what we teach, and how we teach Language teacher education programs should on language teachers who are to social justice and equity in teaching, who are critically aware of the significant impact that contextual conditions may have on language learners’ learning, and who can help language learners develop semiotic resources to assert themselves in contexts. central tenets of dynamic complex system theory with a rich understanding of teacher agency may prepare language teacher educators and language teachers for a understanding of their own professional The DFG framework can also as a map to guide language teachers’ efforts to prepare themselves for the task of learning to create a more equitable world through language teaching. of us a difficult process of in which agency will a critical role in transforming our understanding and our pursuit of professional For the of a more equitable we must and