The results are based on 7,224 face-to-face interviews with a probability sample of youth, young adults, and older adults. For this study, the basic national sample was supplemented by a sample of residents of rural areas. Interviews were conducted from August 1979 through January 1980. In addition to providing information on the extent of the drug abuse problem, this survey describes the various forms in which the phenomenon occurs. Among survey results, findings show tht the highest usage rates of marijuana are among young adults (age 18 to 25). Nearly 7 in 10 (68.2 percent) young adults report experience with the substance and more than one-third (35.4 percent) report current use. Lifetime experience with inhalants has increased significantly since 1977 among both young adults and older adults; 16.5 percent of the young adults report lifetime prevalence. Experience with hallucinogens is reported by one-fourth (25.1 percent) of young adults, 1 in 14 (7.1 percent) youth, and 1 in 22 (4.5 percent) older adults. Similarly, cocaine use is also highest among young adults, with 27.5 percent of the 18-to 25-years olds reporting at least one use of this substance. Reported experience with heroin is 3.5 percent among young adults, 1 percent among older adults, and .5 percent among youth. Concerning alcohol, 95.3 percent of young adults, 91.5 percent of older adults, and 70.3 percent of youth report experience with alcoholic beverages. Experience with cigarettes is reported by 82.8 percent of young adults, 83 percent of older adults, and 54.1 percent of youth. Finally, more than two-thirds of young adults report experience with an illicit substance. Over 100 tables present data on drug use. A glossary and footnotes are included. Information on data quality, sampling and statistical inference, definition of the sample, attitudes, and the interview schedule and related materials are appended. (Author abstract modified)