The function concept is one of the fundamental constructs in school mathematics and teachers need to have a firm and flexible grasp of this construct. Dr Nyikahadzoyi investigated prospective high school mathematics teachers’ understanding of this construct. A sophisticated conceptual framework using historical sources and constructs from mathematical learning theories was constructed to guide the investigation. This framework was applied to prospective teachers’ responses to items related to functions. The conclusion reached is that prospective teachers hold primarily a process conception of a function and this influences the pedagogical decisions that they make. The thesis moves beyond the level of description of students’ understanding of the concept of a function. A revised conceptual framework is proposed. This is the major strength of this dissertation. The revised framework will in fundamental ways influence haw learning experiences will be organized for prospective teachers to graduate with a flexible understanding of the concept of a function.