In spite of a "war on drugs" that spans years, and in spite of increases in law enforcement efforts and to a lesser extent treatment, substance abuse and dependence continue. While the number of people who experiment with drugs has decreased in recent years, those who use drugs repeatedly, per- haps several times a week, a measure of "hard core" drug abusers, has not changed, and emergency room visits associated with substances abuse continues to rise. Considering both licit and illicit drug abuse, the number of drug abusers in, for example, the United States is very large and, accordingly,...