Science educators have recently begun to enact and study new, collaborative forms of professional development. Yet, few recognize that doing so requires contesting historical meanings of "university-school collaboration" and "professional development," both of which may operate to sustain a hierarchy model of collaboration. The hierarchy model maintains the flow of information and knowledge from universities to teachers to students. In science education, the hierarchy model may be strengthened by science's own history of hierarchy. This study describes the authors' attempt to contest the hierarchy model by facilitating a collaborative planning project with elementary teachers. Critical discourse analysis is used as the primary theoretical and methodological tool to (1) explain how the hierarchy model was shaped by and shaped the group's actions, interactions, and identities; (2) explain the complexities of collaboration by moving beyond deficit-based explanations (e.g., blaming individuals or organizational structures); (3) offer theoretical and methodological approaches for understanding better the nature of collaboration and practical solutions for those attempting to challenge the history of hierarchy. In focusing on how meaning is made in interaction, the authors demonstrate how language and interaction are inextricably bound with history and culture.