Mental health and substance use disorders are highly prevalent among incarcerated individuals. Many prisoners reenter the community without receiving any specialized treatment and return to prison with existing behavioral health problems. We consider a Beckerian law enforcement theory to identify different channels through which access to healthcare may impact ex-offenders’ propensities to recidivate, and empirically estimate the effect of access to public health insurance on criminal recidivism. By exploiting variation in state Medicaid expansion decisions, we find that increased access to healthcare through Medicaid coverage reduces recidivism among offenders convicted of violent and public order crimes. The decomposition of recidivism rates shows that this reduction is driven by marginal recidivists who, but for Medicaid expansions, would be reconvicted for the type of crime for which they were previously convicted. Analyses of potential mechanisms show an increase in criminal justice referrals to addiction treatment, which may reduce impulsive behavior. Back-of-the-envelope calculations also indicate that there are substantial cost reductions from providing Medicaid coverage to former inmates.