Since 1976, incarcerated individuals in the United States have an established right to healthcare. This has created a national system charged with addressing the unique challenges of healthcare delivery in jails and prisons. As incarcerated populations are often excluded from large research studies, evidence-based practices must often be extrapolated from community data. There is a wide variation in care delivery across institutions nationwide. Challenges in correctional settings include a “dual loyalty” to patients’ health and facility security and the toxic effects of disciplinary practices including solitary confinement, violence, communicable disease control, an aging population, discharge planning for community reentry, and a high prevalence of substance use disorder and mental health disease. Although incarceration may offer a unique opportunity to address chronic health issues of a difficult-to-reach population, the net health effects in the United States seem to be mostly negative. Mass incarceration in the United States has led to significant health consequences at the individual, family, and community levels and has exacerbated health, socioeconomic, and racial disparities. As most incarcerated individuals return to the community, healthcare delivery during incarceration plays a substantial role in the health of communities at all levels.