Lesson Study, which assumes multiple variations, is a collaborative method that provides an opportunity for teachers to notice professionally. We analyzed how audible conversational components afforded and constrained the verbalization of professional noticing of a lesson study team. The team, comprised of six prospective teachers, a classroom teacher, and a university facilitator, participated in weekly lesson study cycles in a teacher education program. Results indicate that a structured lesson study process afforded professional noticing as participants attended to and analyzed students' thinking. However, noticing was constrained by shifts in the conversation content and lengthy segments of individuals exerting expertise. Findings indicate that the facilitator played a crucial role in increasing the incidence of professional noticing and also contributed to the decline of noticing. Implications for teacher education programs are included.