In mathematics classrooms, teachers are often the authority as a knower of mathematics. To support students to develop their identity as doers of mathematics, teachers need to decenter the authority and to place students in a more powerful position as autonomous thinkers. Building on the work of Herbel-Eisenmann and colleagues (2013), this paper aims to expand the notion of powerful discourse from a conversation analytic approach. By examining the fine-grain epistemic characteristics of interactional sequences, I argue for the significance of the interactional knowledge domain, in which positioning of students as more or less knowledgeable takes place. Further, I discuss the need for examining the discursive dimension of knowledge and discursive practices that can redistribute the epistemic authority in mathematics classrooms. [For the complete proceedings, see ED606556.]