“Professional development with a sustained focus on subject teaching — strongly tied to the curriculum, instruction, and assessment that students would encounter — produces the most consistent effect on subject teaching and student learning. Other professional development emphases, such as using hands-on activities, organizing cooperative small groups, taking steps to increase gender equity, or preparing teachers for leadership roles, certainly respond to widespread interests and concerns. however, none of them shows a consistent relationship to teachers’ conceptions of subject teaching or reported practices of subject teaching. Only the professional development focused on subject knowledge for teaching does so.”