Assessment and evaluation have multiple purposes. First, they support continuous improvement. With data collected in formative and summative evaluations, leaders of professional learning systems have evidence to make improvements. Second, they generate evidence to determine whether the system is working both to support effective professional learning planning, implementation, and evaluation and to improve educator effectiveness and student success. In addition, an evaluation can inform resource investments. For a comprehensive professional learning system to work smoothly and to meet its many goals, all components of the system must be finely tuned and coherent. Recommended steps for the evaluation of a comprehensive professional learning system include: Plan the evaluation; Establish the evaluation framework; Conduct the evaluation; Report the evaluation; and Evaluate the evaluation. Included here are two