Geographical knowledge is powerful if it is critical and empowering. This article develops this argument with reference to the philosophy of knowledge and Laura Wheelahan's advocacy of critical realism as the philosophical strand of her social realist curriculum theory. While the GeoCapabilities Project has drawn on the sociological strand of that theory, its neglect of the philosophical strand means that its concept of powerful geographical knowledge remains ambiguous. Incorporating critical realism, along with critical theory and pedagogy, would allow the project to better realise its aims and open up new directions for research.