Background/Context: The Common Core State Standards Initiative reveals how little we understand about the components of effective discussion-based instruction in disciplinary history. Although the case for classroom discussion as a core method for subject matter learning stands on stable theoretical and empirical ground, to date, none of the research on classroom discussion has examined whole-class text-based discussion in secondary history classrooms. Purpose: This study explored how teachers and students in five 11th-grade classrooms participated in whole-class discussion, using intervention materials designed to promote text-based disciplinary discussion. Analysis of videotaped instruction sought to (a) determine the degree to which the instructional materials fostered disciplinary discussion about texts, and (b) analyze teacher talk moves that characterized effective facilitation of such discussions. Research Design: This qualitative study was embedded in a larger quasi-experimental curricular intervention that found treatment effects on factual recall, historical thinking, and general reading comprehension. In this paper, we analyze classroom videos from five treatment classrooms taken over the course of the six-month intervention. Each teacher was videotaped once per week, for a total of 20 videotaped lessons per teacher. Findings/results: Analyses showed that disciplinary discussion was surprisingly rare, and discussion that promoted historical understanding even rarer. Discussions that were most successful in deepening students' historical understanding were characterized by talk moves that drew students' attention to the text, and that stabilized the historical content. Conclusions/Recommendations: The study has implications for teacher preparation focused on implementation of Common Core State Standards as well as for teacher training in domain-specific core practices.