This paper is one of three major reports documenting the results of a 1984 survey of Maryland adolescents' knowledge of, attitudes toward, and experiences with drugs and alcohol. An introduction briefly outlines the work of the Maryland Drug Abuse Administration and describes earlier surveys. A methodology section describes 1984 sampling techniques and survey administrations which resulted in 33,079 valid questionnaires from 8th, 10th, and 12th grade students statewide. Computation of statewide estimates is explained. The survey results are presented in three parts. Part One furnishes estimates of substance use by Maryland adolescents in four categories: (1) substances used; (2) the severity of substance abuse; (3) the demography of substance abuse; and (4) substances used by adolescents in each geographic subdivision. Part Two examines trends in substance use among Maryland's adolescents by comparing and contrasting statewide and subdivision estimates for 1980, 1982, and 1984. Part Three compares the Maryland results to the results obtained by the National Institute on Drug Abuse in its 1984 annual survey of student drug use in America. The report's conclusion summarizes the findings of the 1984 survey and concludes that drug abuse, as reported by adolescents between 1980 and 1984, has declined in Maryland. Relationships found between demographic characteristics and drug use trends are also summarized. Forty-two data tables appear throughout the text and the Maryland Adolescent Survey 1984 is appended. (NB)