While Shulman argues that an important component of pedagogical content knowledge (PCK) is teachers' understanding of the alternative conceptions commonly held by students, relatively little is known about what students believe about many topics in the school curriculum. This paper focuses on a content area typically featured in Geography curriculum as the first phase of a larger study designed to investigate Geography teachers' PCK. Common student conceptions of tropical cyclone causes and processes were identified using a variety of methods. Results indicate that secondary school Geography students (n = 339) hold a range of alternative conceptions related to foundational scientific principles as well as the geographical concepts of location, scale, spatial distribution, interactions and interdependence. Implications for the knowledge requirements of Geography teachers are discussed along with suggestions for future research. (Contains 6 figures and 3 tables.)