A study analyzed in detail one 37-minute classroom literature discussion to better understand how to foster students' critical reasoning. It investigated the characteristics of classroom interactions that support students in the process of responding to literature, the roles of the participants, and how the teacher can structure the tasks and use language to help students begin with their own initial responses and move beyond, to deeper understanding. Twenty-six seventh-grade English students participated in the discussion. The discussion was then analyzed by segmenting the transcript into turns and then into topics, and speakers' interactions were coded to identify the purposes which lay behind each speaker's turn. Then the broader patterns across the whole discussion were examined to note the patterns of participation and control, the roles played by teacher and students, and the ways in which instructional scaffolding worked in the discussion. Results illustrated how the process of understanding developed through social interaction, and shows that the role of the teacher was crucial in accomplishing this. Results also showed that a heterogeneous class of students with differing reading levels can function well when involved in a group discussion. Results additionally demonstrated the five elements of effective instructional scaffolding that contributed to the success of this discussion: ownership, appropriateness of the instructional task, structure, collaboration, and internalization. (Six tables of data and 34 references are attached.) (PRA)