At ECER 2008 Linda Evans presented in outline her recently formulated ontological model of professional development. This identifies three components of professional development: functional development, intellectual development and attitudinal development, each of which has three further dimensions or change foci (Evans, 2008a). This ECER 2009 paper will expand upon last year’s cursory introduction, illustrating through real examples of professional development how the model may be used to understand better the complexities of professional development, how it may be applied as a theoretical framework for analysing empirical research findings, and how it helps us understand why many top-down change initiatives and reforms do not work as well as the change initiators intended. Evans will draw upon examples from her empirical research in the UK, and also examples of her own professional development as a schoolteacher and as an academic. She will use these to illustrate and demonstrate how the different professional development components and dimensions identified in her model combine to create the professional development process in individuals.