The evaluation design consisted primarily of comparing patients who stayed in the program with those who left the program within 1 year for any reason. Data were collected on the total clinic population as of March 1972; of 678 total patients, 486 (71.7 percent) were still active in the program at that time. Drug use data were gathered from clinic records and patient self- reports. Patients who left the program reported slightly more actual heroin use in the last 7 days prior to starting the program than patients remaining in the program for a year. A revised version of the Sechrest Offense Severity Scale was used to determine the seriousness of criminal behavior before and after the program. Patients who stayed in the program did not dramatically stop all criminal activities but were less likely to participate in serious criminal activities. Patients who stayed in the program were more deeply involved in drug law violations before the program and showed a later reduction in such violations. Patients who left the program showed a significant increase in drug law violations. With regard to employment, no evidence was found of recorded earnings for those who left the program, whereas employment and sometimes increased earnings were observed for those who remained in the program. Patients who came into the program with better job skills tended to remain in the program. Misdemeanor arrests did not change significantly for patients staying in the program at least 1 year, but felony arrests decreased substantially. 1 footnote, 1 table, and 3 charts