We systematically reviewed randomized controlled trials of interventions to improve the health of people during imprisonment or in the year after release. We searched 14 biomedical and social science databases in 2014, and identified 95 studies.Most studies involved only men or a majority of men (70/83 studies in which gender was specified); only 16 studies focused on adolescents. Most studies were conducted in the United States (n = 57). The risk of bias for outcomes in almost all studies was unclear or high (n=91). In 59 studies, interventions led to improved mental health, substance use, infectious diseases, or health service utilization outcomes; in 42 of these studies, outcomes were measured in the community after release.Improving the health of people who experience imprisonment requires knowledge generation and knowledge translation, including implementation of effective interventions.Worldwide, more than 11 million people are imprisoned at any given time, and the prison population continues to grow at a rate faster than that of the general population. 1 Substantial evidence reveals that people who have experienced imprisonment have poor health compared with the general population, as indicated by the prevalence of mental illness, infectious diseases, chronic diseases, and mortality. 2 There are several reasons to focus on improving the health of people who experience imprisonment. 3 The burden of disease in this population affects the general population directly through increased health care costs and through the transmission of communicable diseases (e.g., HIV, HCV, and tuberculosis) after people are released from detention. Imprisonment has also been associated with worse health in family members of those who are detained, compared with the general population, including chronic diseases 4 and poor mental health 5,6 in adult relatives and mortality in male children. 7 At the community level, higher rates of incarceration have been associated with adverse health outcomes, such as sexually transmitted infections and teen pregnancies. 8 There is also evidence that poor health in persons who are released from detention, particularly those with inadequately treated mental illness and substance use disorders, 3 may affect public safety and reincarceration rates, 3 and that better access to health care is associated with less recidivism. 9,10 Finally, the right to health and health care is enshrined in international human rights documents, 11,12 and is a legislated responsibility of governments in many countries.Intervening during imprisonment and at the time of release could improve the health of people who experience imprisonment and public health overall. 13 To address this gap, we systematically reviewed randomized controlled trials of interventions to improve health in persons during imprisonment and in the year after release.We chose this population because we view imprisonment as a unique opportunity to deliver and to link with interventions for this population, and to highlight interventions t...