Whole-class discussion is a common instructional approach used by secondary science teachers. When orchestrated well, such an approach can provide students with opportunities to engage in extensive science talk with the benefit of teacher guidance and feedback. Our study investigated teachers' approaches to discussion during the piloting of an urban ecology curriculum designed to support student participation in science discourse as well as teachers' beliefs about science talk. Participants included five secondary science teachers and their students ("n" = 116). Our analysis focused on transcripts of whole-class discussions and interviews with teachers about their beliefs regarding talk. We found that the students' contributions during discussions were typically limited to simple phrases or short sentence responses that did not voluntarily include reasoning. The teachers' framing of the lessons and the moves the teachers made during the discussions seemed to reinforce the limited nature of the students' responses. Furthermore, we found that teachers rarely used probing questions or tossed back students' ideas. The beliefs teachers expressed about their students, themselves, and external factors provided insight into why teachers continued to take an authoritative stance even though they believed teacher-driven discussion was not the ideal. (Contains 5 tables and 3 figures.)