This article examines the effect of different intensities of legal supervision on the addiction and criminal careers of narcotic addicts involved in the California Civil Addict Program. Legal supervision is defined as probation or parole, both with and without urine testing, and outpatient status (OPS or intensive parole supervision). Results from a study on narcotics addicts admitted to the methadone maintenance programs in Southern California between the years 1971 and 1973 and interviewed in 1978 indicate that legal supervision with urine testing was the most effective form of legal supervision in reducing the percentage of time in daily narcotics use and criminal behavior. 2 figures, 6 tables, and 27 references (Author abstract modified)