BASED UPON INTERVIEWS WITH 2,489 PATIENTS ADMITTED IN 1977 AND 1978 TO A MODIFIED THERAPEUTIC COMMUNITY TREATMENT PROGRAM FOR SUBSTANCE ABUSERS, SUBJECTS WERE DIVIDED INTO THE FOLLOWING GROUPS ACCORDING TO THEIR DEGREE OF CRIMINAL JUSTICE INVOLVEMENT AT ADMISSION: DIRECTLY FROM PRISON, ANY OPEN CASES, PAROLE AND/OR PROBATION, AND NO LEGAL INVOLVEMENT. THE CANDIDATE PROGRAM IS A 4- TO 6-MONTH RESIDENTIAL PROGRAM AVAILABLE TO MOST RESIDENTS UPON SUCCESSFUL COMPLETION OF THE INPATIENT PROGRAM. THE RELATIONSHIP BETWEEN DEGREE OF LEGAL INVOLVEMENT AND COMPLETION OF THESE TWO PROGRAMS WAS MEASURED. RESULTS SHOW THAT MALES WERE SIGNIFICANTLY MORE INVOLVED IN THE LEGAL SYSTEM THAN FEMALES, AND MALES WERE MORE LIKELY THAN FEMALES TO ENTER TREATMENT DIRECTLY FROM PRISON AND TO HAVE MORE PAROLE AND/OR PROBATION INVOLVEMENT; HOWEVER, MALES WERE LESS LIKELY TO ENTER TREATMENT WITH ANY OPEN CASES. RESIDENTS ADMITTED DIRECTLY FROM PRISON WERE MORE LIKELY THAN ANY OTHER GROUP TO COMPLETE INPATIENT TREATMENT. THOSE WITH LEGAL INVOLVEMENT WERE LESS LIKELY TO ENTER THE CANDIDATE PROGRAM THAN THOSE WITH NO LEGAL INVOLVEMENT. OF THOSE WITH LEGAL INVOLVEMENT, THE OPEN CASE GROUP WAS THE MOST LIKELY TO ENTER THE CANDIDATE PROGRAM. MALES WITH LEGAL INVOLVEMENT WERE MORE LIKELY TO COMPLETE INPATIENT TREATMENT THAN MALES WITH NO LEGAL INVOLVEMENT, FEMALES WITH NO LEGAL INVOLVEMENT, OR FEMALES WITH LEGAL INVOLVEMENT. THE DATA SUGGEST THAT LEGAL INVOLVEMENT IS POSITIVELY RELATED TO TREATMENT OUTCOME AND RETENTION. TREATMENT OUTCOME REFERS ONLY TO THE RATE OF COMPLETION AND NOT THE PATIENT'S BEHAVIOR AFTER COMPLETING TREATMENT. A BIBLIOGRAPHY IS PROVIDED. (RCB)