This review explores the rate of problem gambling among criminal offenders. The authors reviewed 27 studies from four countries. Their review shows that about one third of criminal offenders have problem gambling. Additionally, about half of the crimes committed by inmates with problem gambling are related to gambling. It also shows that although most prisons prohibit gambling, it is still very common. About 40% of inmates gamble while in prison. The authors suggest that inmates should be screened for problem gambling. They also suggest that prisons should provide problem gambling treatment programs.