This article explores the views and actions of four science teachers participating in a collaborative action research project. A qualitative case study approach was used to describe and analyze the development of these teachers. This development initially involved the teachers critically comparing their extant practices to current developments in science curriculum, teaching and learning. From this iterative and reflective process, the teachers proceeded to implement curricular changes and reflect again on their modified curricular practices. The authors' analysis of the data suggests that all participants had augmented their personal understanding of both scientific inquiry and the nature of science, and had also developed socially and professionally. Implications for the value of collaborative action research in promoting teacher development are presented. (Contains 2 figures.)