If students are to meet higher standards, all educators in the system have to learn how to engage students in reasoning about complex ideas. What levers can state boards of education and state education agencies pull to support the professional learning that makes this possible? A research-practice partnership in Tennessee may shed light on this question. This group's task was to support mathematics teachers across the state through instructional coaching. This work contributes to a body of research showing that well-designed coaching programs contribute to teacher learning and improved instruction.