The study was designed to determine which psychotropic substances (both licit and illicit) are being used by the population of Amsterdam: in which combinations and to what extent; how the prevalence of drug use changed during the last 3 years; to which social, cultural, geographic, and/or economic characteristics this behavior is related; how drug-use patterns are related to urban lifestyles; and whether it is possible to establish changing patterns of use in an early stage by means of repeated measurement. The survey found that the use of most illicit drugs in Amsterdam has remained stable from 1987 to 1990. The use of licit drugs has significantly diminished since 1987, and the prevalence of abstinence behavior has significantly increased. Consumption of cannabis is primarily by the 16-39 age cohort, where current use hovers around 10 percent. Current (last month) use for cocaine is highest among 30-34 year olds, and highest current use of amphetamines is among the 25-29 year olds. In 1990 as in 1987, the use of illicit drugs is highly associated with specific urban lifestyles which can be found primarily among young households of one or two persons. This demographic group is still growing in Amsterdam, so an increase in the use of drugs can be expected. Research recommendations are offered. Numerous tables and figures