Responses came from 33 countries. Results revealed wide variations in populations of convicted prisoners and pretrial detainees. Three countries had fewer than 50 people in prisons per 100,000 of the country's population; in contrast, 3 countries had more than 500 inmates per 100,000 population. The amount of space specified for each inmate also varied widely; overcrowding prevented adherence to this standard in many countries. Results also indicated declines in inmate populations in countries of central and eastern Europe from the mid-1980s to 1990, followed by increases during the 1990s. The prison populations in most other European countries have gradually increased. The prison population in Canada has been relatively stable since 1991, whereas the prison population in the United States has increased steadily since 1985 and had almost doubled by 1995. Tables and 6 references