This study examines one NSF-funded Collaborative for Excellence in Teacher Preparation and describes the complexities of such a science education reform effort. A theoretical model based in community, culture, and identity is used to address key questions: How did institutional ideologies, structures, policies, and practices influence the Collaborative's success? What unique problems were associated with the university and school partnership? How did K-12 teachers' participation affect their development and the success of the Collaborative? Findings indicate that though K-12 participants were deemed as "pedagogy experts" and shared the inquiry-based culture espoused in the Collaborative, they felt both as project insiders and outsiders. This was due to issues of status between university faculty and K-12 teachers; teachers' less-than-active role in the Collaborative; and the constraints and narrow focus that resulted from long-established institutional, social, and political structures and that marginalized, delegitimized, excluded, and proved unattractive to teachers.