This article lays out a theoretical argument for empirical research that focuses on what happens inside the practices of L2 teacher education. Central to this argument is that it is inside these practices--the dialogic interactions between teacher educators and teachers--where teacher educators can see, support, and enhance the professional development of L2 teachers. Grounded in a Vygotskian sociocultural theoretical perspective on teacher learning (Johnson, 2009), data from an innovative teacher education practice highlight the quality and character of the collaborative teaching-learning relationships ("obuchenie") that unfold in this practice and the role of the teacher educator in providing expert mediation to support novice teachers' emerging conceptualizations of, and initial attempts at, enacting L2 teaching. The article concludes with a call for empirical attention to the design, enactment, and outcomes of the practices of L2 teacher education as essential in order to reclaim the relevance of L2 teacher education in and for the professional development of L2 teachers.