Over the last decade the world has experienced a growing interest in problems associated with the nonmedical use of drugs. This interest has corresponded to areal growth in the extent, diversity, and social impact of the use of alcohol and drugs in many societies. As a result, the amount of research and writing on the subject of drug problems has greatly increased, and it has become very difficult for one individual to keep up with all the relevant literature. There is thus an acute need in the field for critical reviews that assess current developments, and the present series is intended to fill this need. The series is not to be an "annual review" in the usual sense. The aim is not to cover all the work reported during the preceding year in relation to a fixed selection of topics. Rather , it is to present each year evaluative papers on topics in which enough recent progress has been made to alter the general scope in a particular area. Owing to the multidisciplinary nature of problems of drug use and dependence, the papers published in each volume will be drawn from several disciplines. However, some volumes may be devoted to one partic­ ular problem, with individual reviews and papers examining various aspects of it. The composition of the editorial board and the international advisory board reflects these objectives. The editors are members of the senior scientific staff of the Addiction Research Foundation of Ontario.