Studies of persons processed by the criminal justice system have consistently documented a high prevalence of lifetime and regular drug use among this population. Research conducted within the last ten years, based on self-reports of illicit drug use and crime, provides evidence that rates of use are increasing; however, several independent studies have found that approximately half of all new arrestees underreport recent drug use, even in a confidential research interview. While research over the past ten years has firmly established a relationship between narcotics and/or cocaine use and crime, several issues regarding the etiology, prevention, and treatment of illicit drug abuse as well as the nature of drug-related violence require further study. 99 references (Author abstract modified)