In research across professions, the development of professional skill traditionally was seen as a process of accumulation of knowledge and skills, promoted by practical experience. More recently, this view has been modified to incorporate skillful know-how that is progressively acquired by passing through developmental stages, such as novice, competent, and expert. The authors of this article critically review contemporary stage models that are typically applied across professions. Their principal critique is that a focus on stages veils or conceals more fundamental aspects of professional skill development. On the basis of their critique, the authors propose an alternative model that builds on the strengths of previous models while seeking to overcome their main limitations. Finally, the authors outline the implications of their alternative model for professional education, workplace practices, and research on professional development.