The American Stop Smoking Intervention Study Trial (ASSIST), funded by the National Cancer Institute, is the largest public health tobacco-control effort in U.S. history. This initiative supported state and local coalitions in 23 states to control tobacco use through policy and other systemic changes. Community Science facilitated the design of the evaluation, including the development of a logic model, conceptual development and operationalization of systems change measures, and development of preliminary statistical models. We facilitated workgroups of leading scientists, National Cancer Institute staff, and practitioners. We also designed the final evaluation plan and developed an evaluation management plan.