The authors describe changes in DSM-III substance use disorders to be included in the revised version, DSM-III-R. Major revisions include removal of the distinction between "abuse" and "dependence" and broadening the definition of "dependence" to a syndrome of clinically significant behaviors that indicate a serious degree of involvement with psychoactive drugs; creation of a new category of "psychoactive substance neuroadaptation syndrome" for individuals whose physiological adaptations to high doses of psychoactive substances did not arise from their own behavior; use of an identical set of symptoms and behaviors to determine dependence on all different classes of psychoactive substances; and provision of a system for rating severity of dependence.