The purpose of this paper is to review the diagnostic concepts of substance abuse and substance dependence provided in DMS-III, DSM-III-R, and the forthcoming DSM-IV. The review incorporates the principles that there are no infallible criteria for identifying when a person lacks sufficient control over the usage of a drug, that dyscontrol exists on a continuum, that substance use dyscontrol shares many formal properties with behavioral dyscontrol within other domains, and that the diagnosis of a mental disorder should be free of moralistic connotations. We conclude the paper with an alternative proposal, wherein the DSM-IV diagnoses of abuse and dependence are collapsed within one diagnosis of substance dyscontrol disorder and physiological substance dependence is placed with the diagnoses of substance intoxication and substance withdrawal.