Results indicate that cocaine use is increasing dramatically: client admissions increased over 600 percent, and cocaine arrests increased over 300 percent between 1980 and 1984. Changes in arrests and client admissions for marijuana and narcotics appeared random, indicating a relatively stable pattern of use. During the study period, the proportion of individuals 26 years and older increased in both the arrest and client populations for all types of drugs. Females constituted a higher proportion of the client than the arrest population, especially for problems with tranquilizers. In 1984, almost four times as many individuals sought services for heroin problems than were arrested for heroin violations. Blacks represented half the heroin client population, but almost 90 percent of those arrested. In 1984, there were 8,308 arrests for marijuana violations but only 2,115 marijuana client admissions. Results indicate that persons arrested for drug law violations are greatly underrepresented in the client population and suggest that more effective intervention and treatment services are needed for this group. 9 figures and 29 tables.