Addressing in-service teacher professional development is a significant issue for educational stakeholders as reform movements mobilize to replace teacher-led instruction with student-centred pedagogies. Teachers need access to high-quality professional development to mitigate implementation problems associated with reform practices. Drawing on critical ethnography, I followed the year-long professional journey of six in-service science teachers in Quebec, Canada. Video-recorded professional development meetings and semi-structured interviews captured how teachers worked to enact sophisticated inquiry-based teaching practices. I have used a Bourdieusian lens to examine teachers' shifting habitus as they professionally develop in collaborative professional development. Findings suggested that the field of educational reform is transformative when teachers engage with a professional learning model emphasizing critical reflection and collaborative discourse. Using Bourdieu's concept of habitus and field, findings illustrate the benefits of pedagogic work on teachers' repertoires of practice to understand the generative potential of professional development to transform teachers' instructional practices.