While classroom discussion is often cherished as a cornerstone of effective social science teaching, knowledge on when and where discussions tend to turn deliberative is lacking. To make up for this lack of knowledge, the present study examined classroom discussion in three conditions: a whole-class condition, a small group condition, and a pair condition. The study made use of video observations from a classroom intervention to evaluate how each condition affected the deliberative quality of the discussion process. To this end, 585 student utterances were coded for aspects of deliberation using the Stromer-Galley observation manual. The results showed that both the small group and pair conditions promoted key aspects of deliberation compared to the whole-class condition. The small group condition generated the highest levels of contestation and engagement, whereas the pair condition generated the highest level of equality. While these results suggest that the deliberative quality of classroom discussion might sometimes benefit from the teacher's absence, more research is needed to determine the circumstances in which this is likely to be the case.