The mentor-preservice teacher hierarchy, that privileges mentor teacher talk and experience, often dominates mentor-preservice conversations. To realize the full potential of teacher education approaches designed to engage preservice and mentor teachers together in shared learning and teaching tasks, attention is needed to better understand the dynamics and implications of mentor-preservice teacher interactions. We analyzed how and when preservice and mentor teachers introduced ideas to group conversations and whose ideas were taken up by the group during a co-learning task. We found that mentor teachers tended to dominate group sense-making. However, preservice teacher use of imagination, the actions of teacher educators as brokers, and the use of boundary objects temporarily interrupted the dominant hierarchy. We conjecture that these moments raised preservice teacher status within the group so that mentor teachers took up preservice teachers' ideas. Implications for promoting more equitable preservice teacher participation in sense-making with mentor teachers are discussed.