It is commonly understood that teachers in secondary school should develop throughout their career in order to stay as an essential factor in student learning. Schools can offer opportunities to link teachers' professional learning to their school practice with a positive impact on teachers' motivation to learn and the effectiveness of their learning. In this field study, teachers, school leaders, policy-makers, educational consultants and educational scholars were asked for their perceptions of conditions for teacher learning in school and of interventions in school to enhance teacher professional learning. These conditions and interventions were understood as affordances in schools that enable and support teacher professional learning. The main affordance in school these stakeholders mentioned was an open, but critical way in which teachers share their practices, collaborate and reflect upon their teaching practice. Collaborative practices seem to stimulate many interventions of teacher professional learning in school. Two implications of this finding are discussed. First, we suggest that the maximum teaching time should be reduced, team teaching should be more implemented or classes should be scheduled in such a way that teachers can meet. Second, distributed leadership approaches match with our findings about the role of school leaders in teacher professional learning.