In the spring of 1987, a survey was conducted of 2,700 seniors in 37 overseas schools of the Department of Defense Dependents Schools (DoDDS) system, replicating an earlier 1982 survey. Both matched a parallel series of domestic national surveys in the ongoing Monitoring the Future study. This report presents the findings on the prevalence of drug use and related factors among both DoDDS and stateside seniors in 1987, and also compares trends between 1982 and 1987 for both populations. After an introductory overview of key findings, the study presents the survey outcomes with respect to the following: (1) prevalence of drug use over all and among important subgroups; (2) trends in drug use among high school seniors, both DoDDS and stateside; (3) drug use at earlier grade levels; (4) degree and duration of highs; (5) attitudes and beliefs about drugs, including perceived harmfulness and personal disapproval of drug use; and (6) the social milieu, including current perceptions of friends' attitudes, exposure to drug use by friends and others, implications for validity of self-reported usage questions, perceived availability of drugs, and perceived risks of apprehension and punishment for drug use. The survey includes estimates of sampling variance and trends in willingness to be honest about drug use. (TE)