The purpose of this study was to understand how teachers and graduate-level scientists negotiated differing knowledge bases to work together to improve science teaching and learning. Partners' coparticipation in and dialogue about pedagogical decisions and actions were analyzed. Three theoretical representations of dialogic interactions emerged from this analysis: knowledge negotiation, consultation, and rejection. Knowledge negotiation was a sustained inquiry stance involving intentional actions to understand each other's knowledge representations. This was theorized as having the most potential for transformation of the cultural resources associated with science education. Only one of the nine partnerships in the study was characterized by knowledge negotiation. To explain this, the extensive support for university partners in creating a dialogic community is contrasted with the lack of support for participating teachers. The existence of power differentials between partners and the relevance of this to knowledge consultation are also discussed.