This paper presents a case study of the work of two teacher educators with an in-service science teacher. This case study forms one cycle of a larger action research study that will eventually lead to a model of how the third-space concept for teacher professional development can be realized in natural school settings. The case study took place in…

This study examines how high-quality professional development can promote the diffusion of effective teaching strategies among teachers through collaboration. Drawing on longitudinal and sociometric data from a study of writing professional development in 39 schools, this study shows that teachers' participation in professional development is…