This article provides a model for the professional development of elementary science teachers. The model focused on integrating different domains of knowledge into science teaching, including the knowledge of the science curriculum, especially scientific inquiry, teacher's knowledge, and students' knowledge. The two case studies in this article revealed that the teachers construct their knowledge in a social context. The constant reflections on the experiences helped them to generate alternative teaching approaches. The findings suggest that the model of the project had two functions. First, it provides a useful strategy to help science teachers to bridge the gap between theories of teaching and their own teaching practices. Second, it provides a social learning environment for learning how to teach science.