Drug abuse has been a major social problem in the United States for almost a century and we are now in the second decade of a continuing war on drugs. Drug abuse is a health and criminal justice problem that also has implications for nearly every facet of social life. It is a major element in the high cost of health care, a central reason for the United States's extraordinarily high rate of incarceration, and a focus of intensive education and treatment efforts. Substance abuse is an equal-opportunity problem that affects both high- and low-income persons, although its consequences are most often felt by those persons and communities that have the lowest social capital.

Substance abuse, with its connotations of disapproval or wrong or harmful or dysfunctional usage of mood-modifying substances, is a term that was developed in the United States. The more neutral term, dependence...