Researchers in science education have for some time recognised the need for teachers to develop an awareness of students' common alternative conceptions--a key element of pedagogical content knowledge (PCK)--and use this knowledge to develop student understanding (Morrison & Lederman, 2003). Less attention, however, has been devoted to the investigation of geography teachers' awareness of and work with students' ideas. This paper outlines what is currently known about the nature of alternative conceptions in physical geography, teachers' knowledge of these ideas and their use of this knowledge to inform instruction. The paper proposes a framework to explain the factors affecting the development of geography teachers' knowledge in this area and their application of this knowledge in the classroom. Implications of the framework for pre-service training, and the accreditation and ongoing professional learning of geography teachers, are discussed along with directions for future research.