This is a report on progress during the fourth year of the Center, the aims of which are to continue a program of social science research and training in the study of drug use. Research (much of it longitudinal) has focused particularly on the factors contributing to change in drug behavior among youth in a variety of cultural settings in the U.S. and on drug use in other countries. During this period data from several longitudinal studies of adolescent drug use in the U.S. have been analyzed and reported; data from comparative studies in Israel France and Greece have also been analyzed. Other activities during this period include the publication of a book on longitudinal research drug use; the publication of a monograph on alcoholism, other drugs and violent death in New York City; holding an international conference on the utilization of social science research in making and implementing drug policy; and the continuation of a Columbia University Seminar on Drugs and Society. Objectives for the coming year include: comparative studies of drug use referred to above and publishing the proceedings of the conference on the uses of research in drug policy making.