Information sources include the 1985 National Household Survey on Drug Abuse, the 1986 High School Senior Survey, the Drug Abuse Warning Network through 1986, and the Client Oriented Data Acquisition Process through 1984. The national surveys showed increasing drug use from the early 1970's through 1979, with a general decline during the 1980's. The decline in drug use among high school seniors continued with the class of 1986, following a brief interruption in the downward trend for the class of 1985. National surveys show that cocaine use is an exception to the general pattern of decline. Although the general trends are encouraging, many experts believe that the level of drug use in the United States is higher than that in any other industrial nation. More than half of American youth try an illicit drug before they finish high school. The number of people admitted to emergency rooms following cocaine use more than quadrupled between 1982 and 1986. Drug use is still a major public health problem that is pervasive in extent, diverse in its manifestations, and constantly changing. Data tables.