There is an increased focus in teacher education on research-based teaching as a means to develop a more research-based professional knowledge. However, research from several Western countries shows that neither school-based nor university-based teachers are familiar with how to integrate research-based knowledge in professional teacher practice. Third-space collaborative partnership models between university-based and school-based teachers, who share responsibility for student teachers' learning, have been promising. However, research shows the implications of partnerships as being unbalanced; the university retains control over the definition and delivery of knowledge, and most activities take place on campus. This action research study focuses on how adaptive joint supervision between school-based and university-based teachers is carried out with regard to student teachers' action learning projects. This process initiated mutual learning and understanding of research-based knowledge between the participants in a non-hierarchical, authentic partnership. The present study shows how this can become a supervision model for developing partnerships and mutual understanding of research-based knowledge between universities and schools, in respect of student teachers' professional development.