Two federal reports dating from 1999 and 2006 are by far the most widely cited sources for the prevalence of mental illness among persons in U.S. jails and prisons. To provide a broader picture of the issue, the author undertook a systematic review of 28 articles published between 1989 and 2013. Not only did the review confirm the high prevalence of mental illnesses among prisoners, it identified a litany of health problems associated with the incarceration of persons with mental illness and profound difficulties in finding housing and employment after release.