We know little about the challenges districts and teachers face when establishing Ethnic Studies courses. In one school district, variation in teachers' Ethnic Studies knowledge impeded the production of curricula and its implementation. This study examines how Ethnic Studies teachers responded to the problems of differential knowledge and orientation on race, power, and teacher positionality in the context of high school classrooms. Based on participant observation and semi-structured interviews, I argue that a praxis-oriented approach to teacher professional development can play a central role in preparing Ethnic Studies teachers. Through political education and critical race dialogue, teachers developed their critical consciousness, which then led to a collective identity and shared views on major elements of Ethnic Studies' curricular perspectives and approach. This study holds significant implications for teacher education and professional development as schools, districts, and states create policies to contribute to an equitable and inclusive public education through Ethnic Studies curricula.