A brief description is given of the Bellack System, which is used to analyze the content and structure of discussion. The system identifies who speaks, when they speak, and what they say. Four types of pedagogical "moves" were identified by Bellack: (1) a structuring move--beginning a new topic; (2) a soliciting move--a question; (3) a response move--a reply to a question; and (4) a reaction--a comment following a response. In this study, a group of 26 sixth and seventh grade students and their teacher were observed during social studies discussion sessions for a period of 16 weeks. The discussions, which lasted from 20 to 40 minutes, were audiotaped, transcribed, and analyzed by an adaptation of the Bellack System. (JD)