The article focuses on school-based development and how collaboration between teacher educators and leaders and teachers can promote development in teacher education, in school and in the collaboration site in school where both parties meet. The data were collected in Norway through qualitative interviews with groups of teachers and leaders at three schools, and with a group of teacher educators. With the Cultural Historical Activity Theory as the framework, central concepts within this theory have been key elements in the study. The findings reveal that collective collaborative learning is a positive form of enhancing the professional development of teachers and that both structure and culture should interact when fostering development in school. The study also shows that the development of teacher educators' research competence can enhance development and learning both in teacher education and in school, and also improve the developmental transfer between these two arenas.