Books by education experts and speakers at national professional conferences have inspired many school leaders to initiate professional learning communities (PLCs). Sustaining them effectively to raise student achievement is another matter. How can one know whether a PLC is moving toward a desired outcome? Measuring effectiveness requires an ongoing process of aligning goals, documenting progress with evidence and coaching for continuous improvement. Based on their work with schools and districts, the authors have found two key assessment strategies help them gauge the impact on professional learning and student achievement. The first strategy tightly aligns student learning goals with professional learning goals, cultural learning goals and structural learning goals. The second strategy involves systematic coaching using evidence for continuous improvement. The authors discuss these two key assessment strategies which they have observed in action in 16 school districts involving 57 schools, elementary grades through high schools, ranging from large urban to small rural schools.