The U.S. has one of the highest incarceration rates in the world, with over seven million individuals admitted to jails each year. These incarcerated individuals are the only group in the U.S. that have a constitutional right to receiving "reasonably adequate" health care. Yet, there is little oversight and funding for health care in jails, where illness and mortality are rampant. In this study, we randomize the offer of health care accreditation to 44 jails across the U.S. Surveys of staff indicate that accreditation improves coordination between health and custody staff. We also find that accreditation improves quality standards, reduces mortality among the incarcerated, which is three times higher among control facilities than official estimates suggest. These health gains are realized alongside suggestive reductions in six month recidivism and are highly cost effective.