Dr. Galanter is professor of psychiatry and director of the Division of Alcoholism and Drug Abuse at New York University School of Medicine, 550 First Avenue, New York, New York 10024. This paper was presented as the Seymour Vestermark Award lecture at the annual meeting of the American Psychiatric Association held May 18-23, 2002, in Philadelphia. This is the final contribution solicited under the editorship of Richard J. Frances, M.D., who has been the editor of Alcohol & Drug Abuse since 1990. Sally L. Satel, M.D., is the new column editor.