Robust data measurement systems assess health care performance and monitor population-level treatment trends. A key challenge in the assessment of substance abuse treatment is the development of systems to accurately monitor service delivery indicators. Wait time to treatment, as defined by the days between first request for service and first treatment, is an important measure of organizational process and delivery of care. The Network for the Improvement of Addiction Treatment emphasizes wait time as a primary outcome in their study of 201 addiction treatment agencies in the USA. This article describes the changes made in five state data systems to monitor wait times and outlines lessons learned that could be applied to other health data tracking systems.