The findings show clear ethnic group differences in drug use. White arrestees were most likely to report the use of heroin and alcohol; Black arrestees were most likely to report the use of cannabis; mixed-race arrestees were most likely to report the use of crack cocaine; and Asian arrestees were least likely to report the use of an illicit drug. Contrary to the stereotype that most drug users are from ethnic minority groups, this research shows that drug use is more prevalent among Whites. White arrestees were significantly more likely to use each of the selected drug types (except for cannabis) and to use them at a higher rate (except for cocaine powder) than Black and Asian arrestees. Consistent with previous research, White arrestees were also significantly more likely to inject illicit drugs and to be dependent on them. This article explains how these findings regarding distinctive drug-use patterns according to ethnicity have implications for drug treatment policies and future research. During the 3-year research period (1999-2002), surveys were conducted among arrestees held in custody in 13 police-force areas across England and Wales. The surveys aimed to sample 100 percent of arrestees considered eligible for interview. A total of 15,393 arrestees were processed during the research period, and approximately 60 percent (8,768) were deemed eligible for interviews. The main method of data collection was a personal interview with a structured questionnaire, which included questions on self-reported use of 19 illicit drug types and offending behavior in relation to 11 income-generating crimes. 10 tables and 15 references