History classrooms remain stubbornly resistant to instructional change. We explored whether using classroom video to help teachers identify curriculum-embedded opportunities for student discourse improved their understanding and facilitation of document-based historical discussions. We observed a relationship between teachers' capacity to notice curriculum-embedded opportunities for student discourse in classroom videos and their growth in enacting document-based history discussions. For three of four teachers, the intervention appeared to improve both their analysis of document-based discussion facilitation and their enactment of the practice. Teachers' incoming proficiency and familiarity with document-based history instruction appeared to inform their experience throughout the intervention. We discuss implications for practice and future research on professional development for history teachers.