Types and sequences in patterns of drug use involvement were similar among high school students and graduated seniors, and among youths who differed in sex, family educational background, and race. Four major stages of drug use involvement were identified: beer and wine, tobacco and hard liquor, marijuana, and other illicit drugs. Beer and wine were used overwhelmingly as the entry drugs in the continuum of drug use. Four times as many youths progressed from beer and wine to hard liquor than to cigarettes. However, most cigarettes smokers eventually progressed to drinking hard liquor. Joint use of hard liquor and cigarettes was associated with the highest rates of entry into illicit drug use. Almost no adolescents progressed to other illicit drugs without first using marijuana. Deviations in the patterns of drug use frequently developed in later steps in the sequence. 6 tables, 1 figure, and 30 references