This study investigated how instructors engage preservice teachers (PSTs) in whole-class discussion in mathematics classes for PSTs. Participating in discussions of mathematical ideas by explaining mathematical ideas to others and responding to others' ideas and arguments might be beneficial for PSTs both to help them develop deeper knowledge of mathematical concepts and to give them experience participating in the types of discussions that teaching reforms call for them to use in their future classrooms. Unfortunately, although we know a great deal about whole-class discussion in K-12 classes, we know surprisingly little about discussions in undergraduate classes and even less about discussions in courses for future teachers. Because of the paucity of relevant postsecondary research available, this study used research on K-12 classrooms that highlighted important factors for productive discussions as a guide to investigate whether teaching moves that are useful in K-12 contexts are used and useful in classes for PSTs. Specifically, this study focused on two teaching moves that happened in class before whole-class discussion (what activities preceded whole-class discussion and what kinds of discussion prompts instructors used to encourage discussion) and four teaching moves that occurred during whole-class discussion (how students were chosen to talk in discussion, how instructors responded to student thinking, how student thinking was connected to other student thinking, and how student thinking was explicitly connected to mathematical ideas in discussion). This study used videotaped observations of fractions lessons, collected as part of a larger research project, to investigate how two experienced instructors facilitated whole-class discussion in a mathematics class for preservice teachers. Summaries of the videotapes were examined for patterns in each practice within and between the two instructors. The results suggest that many teaching practices that have been shown to be effective for promoting discussion in K-12 classrooms are used and useful in classes for PSTs. Before whole-class discussion began, instructors gave PSTs time to think about and work through discussion prompts (often with small groups of peers) before PSTs were expected to discuss with the whole class and instructors often chose discussion prompts that asked students to describe or explain processes rather than repeat facts from earlier in the lesson. During the whole-class discussion, instructors used many methods to choose PSTs to speak in discussion, often asked PSTs to explain their responses further, and made sure PSTs responses were audible and visible for all students. Instructors also led PSTs to correct errors in peer responses and to connect their ideas to peer responses while instructors were often responsible for explicitly connecting student thinking to mathematical ideas. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]