The data also show the grade level at first drug use, trends in use at earlier grade levels, the intensity of drug use, attitudes and beliefs among seniors concerning various types of drug use, and their perceptions of certain aspects of the social environment. The 11 classes of drugs discussed are marijuana, inhalants, hallucinogens, cocaine, heroin, other natural and synthetic opiates, stimulants, sedatives, tranquilizers, alcohol, and cigarettes. The overall use of illicit drugs continued the decline of recent years in 1984, especially in the use of marijuana. Alcohol use has remained at relatively stable and high levels, with 93 percent of the high school seniors having used alcohol at some time and 39 percent having engaged in heavy drinking at least once during the previous 2 weeks. The rate of cigarette smoking also declined. However, 62 percent of all young people try an illicit drug before they finish high school and 1 in 20 seniors smokes marijuana daily. This Nation's youth have the highest levels of illicit drug involvement of any developed nation. Figures, tables, and footnotes.