This article focuses on the processes that come into play as part of a school development project and how these processes contribute to strengthening teacher professionalism. Through processes of consciousness raising and the development of learning cultures where tacit knowledge becomes explicit and shared, and new practices are tested out and discussed, teacher professionalism is developed further. The study shows that this kind of school development work gives the teachers ownership of the development process and strengthens their consciousness about their own teaching as well as develops the learning cultures at the school. Thus, this development becomes an important way in which to reinforce the teachers' professional knowledge, responsibility and autonomy.