This study compares lifetime prevalence and age of first use (onset) for alcohol, cannabis, and other drugs in six international sites. Data from seven epidemiologic field surveys that used compatible instruments and study designs were compiled for cross-site analyses by the International Consortium of Psychiatric Epidemiology (ICPE). The world health organization's composite international diagnostic instrument (WHO-CIDI) and additional items were used to ascertain drug use in each site. Lifetime use rates were estimated for alcohol, cannabis, and other illicit drugs. Survival analyses were used to estimate age of onset. Study settings and main results: use of alcohol twelve or more times ranged in descending order from the Netherlands (86.3%), United States (71.7%), Ontario, Canada (71.6%); São Paulo, Brazil (66.1%), Munich, Germany (64.9%), Fresno, California (USA) (51.9%), to Mexico City (43.2%). Use of cannabis five or more times in a lifetime ranged from 28.8 in the United States to 1.7% in Mexico City, and other drugs ranged from United States (19.4%) to Mexico City (1.7%). Age of first use was similar across study sites. This study demonstrates the fundamental uniformity of onset patterns by age as contrasted with wide variations in lifetime prevalences across sites. Study findings suggest that drug use patterns may change among emigrating populations from low consumption nations as a consequence of international resettlement in nations with higher rates. Methodological limitations of the study along with recommendations for future international comparative research are discussed.