This article draws on two research studies concerned with student teachers' learning of subject-specific pedagogical knowledge: a naturalistic study within two secondary school science departments and a collaborative action research project focused on two contested aspects of the history curriculum. Both confirmed the complexity of the process by which teachers' pedagogical constructions are created and the many components they comprise. The first study revealed rich opportunities for student teachers to observe and engage collaboratively in such processes within subject departments which have a strong geographical location in a team room, and the confidence among staff to admit problems and seek advice. In contrast, the second project's explicit focus on contested aspects of the curriculum saw mentors questioning a critical component of their pedagogical constructions. This inhibited the range of examples they shared with student teachers and their willingness to engage collaboratively with them in creating new ones. Paradoxically, close collaboration between mentors and tutors effectively restricted opportunities to learn from different conceptions of the subject held within the school department. Together the studies raise important questions about the most effective ways of making accessible to student teachers the subject-specific pedagogical knowledge held across the epistemic communities of subject departments. (Contains 1 figure and 1 note.)