There is a strong international interest in the enhancement of teaching quality. Enhancement is a big job because teaching is an extensive activity. It is a complex job because learning to teach is not, mainly, a formal process: non-formal, practice-based learning is more significant. These two points, extensiveness and practice-based learning, lead to the claim that enhancing the quality of teaching implies the creation of working environments that favour certain kinds of professional formation. This analysis is different from mainstream thinking about educational professional development and has significant, systemic implications for quality enhancement practices and suggests fresh directions for quality enhancement research. (Contains 3 tables.)