Fierce debates over standardized assessments in teacher preparation have revolved around flaws in implementation and the politics of privatization. While important, this focus obscures the philosophical divide between proponents and opponents of standardized assessments. This article examines how faculty in New York State argue for and against a controversial performance assessment for teacher candidates, the edTPA. Revealing the distinctive ways that teacher educators on opposing sides of this debate understand the nature of knowledge, human development, professionalism, and social justice clarifies what is at stake in debates over how to prepare teachers. Such clarification can deepen the discussion on how to evaluate learning and growth as well as enrich the conversation on how to protect the integrity of educational professions and practices.