This chapter offers a systematic survey of leading cognitive models of musical development and treats them not simply as age-based descriptions but as competing accounts of musical thought. It discusses the frameworks of Howard Gardner, Keith Swanwick and June Tillman, David Hargreaves and Maurice Galton, together with the concepts developed by Mary Louise Serafine and Jeanne Bamberger. The chapter compares their assumptions about the structure of musical abilities, the role of experience, and the transition from intuitive to reflective musical action. In doing so, it shows how these theories can serve both as a map of musical growth and as a practical guide for educational planning. A key conclusion is that no single model is sufficient on its own, whereas their comparison broadens the pedagogical perspective.