The premise of this paper is that the interactional practices constituting teacher-student interaction and language learning are interdependent in that the substance of learners' language knowledge is inextricably tied to their extended involvement in the regularly occurring interactional practices constituting their specific contexts of learning. After laying out the central components of a theoretical framework for understanding the interdependent nature of interaction and learning, I provide an overview of the Initiation-Respond-Feedback organization (IRF), a ubiquitous classroom interactional practice, and then examine two instances of the IRF taken from two language classrooms. I pay particular attention to actions in the IRF that give shape to learners' developing understandings of, and skills for, using the target language. After briefly discussing the likely consequences of extended participation in the IRF in terms of L2 outcomes, I suggest directions for future research. [This article represents a revised version of a lecture presented on September 30, 2008, at the Language Institute of the University of Wisconsin-Madison.]