The aftercare program provides urine surveillance along with a variety of counseling and other drug treatment services to drug-dependent probationers and parolees under Federal supervision. The subjects were clients of seven Federal probation offices and entered the aftercare program between July 1, 1982, and June 30, 1983. Program outcomes and treatment services received were tracked for each offender for up to 1 year following entry into the program. More than 60 percent of the offenders were parolees, and about 22 percent had been convicted of a violent crime. About 54 percent had had some form of drug treatment prior to enrollment in the aftercare program. About 69 percent had a documented history of regular heroin use. About 38 percent of the offenders were terminated from the aftercare program during the first year. About 63 percent showed at least one positive urine sample, about 27 percent had at least one arrest during the followup, and about 41 percent were charged with at least one technical violation of probation or parole. The percentage employed increased steadily during the study period to about 60 percent. Prior use of methadone was the variable showing the strongest relationship with continued drug use. None of the treatment service variables had a statistically significant impact on continued drug use. However, more frequent counseling sessions and office visits were associated with a lower chance of arrest during the first year of the program. Tables, footnotes, and appended study instrument and data tables.