This chapter describes a two-year part time Masters to educate teacher educators, including school-based mentors, and looks at how aspects and activities from this course could support the development of geography mentors’ practice. It begins by setting out some of the key challenges suggested in the literature for the education of beginning geography teachers, raising a number of concerns about the expertise and training of school-based geography mentors. The chapter then considers some theoretical perspectives about the knowledge base of teacher educators to be effective practitioners and some key approaches to support this learning focussed around inquiry approaches to teacher educator learning. Next the structure and rationale of the Masters in Teacher Education are described, showing how the Masters has been informed by these key theoretical perspectives and how it has been designed to support teacher educators’ learning whilst on the job. Finally, drawing on ideas and activities from the Masters in Teacher Education, the chapter suggests three tasks that mentors could undertake to address some of the concerns and challenges that have been identified in the education of geography mentors.