Moving beyond the historical and theoretical traditions that have defined teacher education in TESOL over the last quarter century, in this introductory piece we argue for a reconceptualization of the knowledge-base of ESOL teacher education. Essential to this reconceptualization is the premise that the institutional forms and processes of teacher education frame how the profession responds to the basic sociocultural processes of learning to teach. As such, our teacher education practices constitute our professional self-definition. We argue that the core of the new knowledge-base must focus on the activity of teaching itself; it should center on the teacher who does it, the contexts in which it is done, and the pedagogy by which it is done. Moreover, this knowledge-base should include forms of knowledge representation that document teacher learning within the social, cultural, and institutional contexts in which it occurs. Finally, we believe the knowledge-base of language teacher education needs to account for the teacher as a learner of teaching, the social context of schools and schooling within which teacher-learning and teaching occur, and the activities of both language teaching and language learning. This tripartite framework calls for a broader epistemological view of ESOL teacher education, one that accounts for teaching as it is learned and as it is practiced; we argue that it will ultimately redefine how we as teacher educators create professionals in TESOL.