This report reviews five studies dealing with drug abuse and adolescence and presents an overview of the social changes which have contributed to the increased use of marijuana and other illicit drugs. The importance of the longitudinal study as a research tool is emphasized in describing the research projects that deal with the epidemiology of drug use, personality and sociodemographic factors, peer influence, the relationship between delinquency and drug use, and its biomedical consequences. The report closes with an executive summary, discussion, and suggestions for further research. An annotated list of NIDA (National Institute of Drug Abuse) research monographs is included. (JAC)