More than 8.75 million people are being held in penal institutions around the world, either as pretrial detainees or as sentenced inmates. Based on world population data for 2002, this means that approximately 1 out of every 700 persons in the world is in a penal institution. At the end of 2001, the United States had the highest prison population rate in the world, at 686 inmates per 100,000 population. The Cayman Islands, a small Caribbean territory, was second. Crime rates alone do not explain the high imprisonment rates in many countries, since trends in crime rates do not correlate with trends in imprisonment rates. Andre Kuhn (1997) attributes high imprisonment rates to fear of crime, loss of confidence in the criminal justice system, disillusionment with treatment effectiveness, and commitment to retributive philosophies of punishment. Large prison populations are of concern because they result in prison overcrowding, deteriorating prison conditions, reduced staff-to-inmate ratios, and less effective inmate treatment programs. The result is that inmates are unprepared to change their criminal lifestyles when they are released from prison back into the community. Recommendations for reducing prison and jail populations are to curtail and shorten pretrial detention, expand correctional alternatives to incarceration, and shorten prison sentences. 2 tables, 2 figures, and 5 references