There is strong evidence that the summer courses led to significant changes in teachers' mathematics content knowledge and understanding. Furthermore, evidence from subsequent classroom observations indicated changes in teacher practice as a result of their experiences in the summer workshops. Baseline RTOP data from Year 1 suggested classroom contexts that were largely teacher-directed, didactic, whole-group, and focused on delivery rather than inquiry and discourse. The results from Years 2 and 3 showed substantial improvement on each of the scales, supporting the idea that improving teachers' content knowledge in mathematics helps to improve their instruction in mathematics. Further analysis is necessary to make definitive conclusions.