Improving prison health care requires a robust measurement dashboard that addresses multiple domains of care. We sought to identify tested indicators of clinical quality and access that prison health managers could use to ascertain gaps in performance and guide quality improvement. We used the RAND/UCLA modified Delphi method to select the best indicators for correctional health. An expert panel rated 111 indicators on validity and feasibility. They voted to retain 79 indicators in areas such as access, cardiac conditions, geriatrics, infectious diseases, medication monitoring, metabolic diseases, obstetrics/gynecology, screening/prevention, psychiatric disorders/substance abuse, pulmonary conditions, and urgent conditions. Prison health institutions, like all other large health institutions, need robust measurement systems. The indicators presented here provide a basic library for prison health managers developing such systems.