This article describes the case of a professional community of high school Pre-algebra teachers who began and later abandoned a collective effort at reform. The community's retreat from reform appears to have been influenced by their beliefs about students and their closely related beliefs about appropriate content and pedagogy for those students. Both sets of beliefs were characterized by conflict and internal inconsistency. Yet, the community avoided addressing the conflicting nature of their beliefs. Both the nature of the community's beliefs and their avoidance of the inherent inconsistencies appear to have shaped the response to reform in this case.