Globally, there is a political and social consensus that teacher education is a key priority for the twenty-first century. However, studies have so far paid little attention to a crucial issue, namely, leadership in teacher education. This chapter contributes to discussion on transforming teacher education practices by focusing on leadership practices in a particular Finnish teacher education department. Adopting a subject-centred sociocultural approach, we elaborate the main challenges, insights, and lessons learned, as perceived by the four leaders of the department, in efforts to move towards more innovative and collaborative practices. We argue that teacher education leaders currently require competencies to support professional agency and to lead the identity work of their staff. In addition, leaders need the resources to build collective leadership practices while renegotiating their own professional identities. Overall, we highlight the importance of what we term collective agency-promoting leadership in developing teacher education practices.