Argentina, Brazil, Costa Rica, Japan, Jordan, Italy, Malaysia, the United States (State of New York), Singapore, Sweden, and the United Kingdom participated. In each country, local researchers conducted the study following a plan developed for the whole project. The multidisciplinary methodology included four phases: a comparative analysis of antidrug legislation, preliminary national reports, eight vignettes administered to different groups to gain information on the perceptions of the justice system, and guided interviews conducted with drug addicts. The data were quantified, and evaluation scales were constructed for purposes of comparison. Binary automatic scoring was applied to data from the vignettes and interviews. The data are shown graphically in 97 tables. Three conclusions are emphasized. First, drug abuse is apparently both quantitatively and qualitatively more serious where the system is perceived as less harsh and more permissive. Second, a significant correlation exists between knowledge of the law and the efficacy of the system. Third, a close association exists between the abuse of drugs and criminal behavior. These points are important for policymakers to consider. The studies in New York, Sweden, and the United Kingdom are outlined. Attachments include a 560-item bibliography and a list of experts and researchers involved in the study. Other publications from the United Nations Social Defense Research Institute are also listed.