Understanding language teachers’ mental lives (Walberg, 1972), and how these shape and are shaped by the activity of language teaching in diverse sociocultural contexts, has been at the forefront of the sub discipline of applied linguistics that has become known as language teacher cognition. Although the collective research efforts within this domain have contributed critical insights into what language teachers know, believe, and think in relation to their work (cf. Borg, 2006), limited progress has been achieved in addressing some of the most pertinent questions asked by applied linguists, policy makers, and the general public alike: How do language teachers create meaningful learning environments for their students? How can teacher education and continuing professional development facilitate such learning in language teachers? By revisiting the domain's epistemological, conceptual, and ethical foundations, this special issue sets an agenda for reinvigorated inquiry into language teacher cognition that aims to redraw its current boundaries and thus reclaim its relevance to the wider domain of applied linguistics and to the real‐world concerns of language teachers, language teacher educators, and language learners around the world.