THE 116 MEMBERS OF THE EXPERIMENTAL GROUP WHICH PARTICIPATED IN THE REHABILITATION PROGRAM DURING ITS INITIAL 3-YEAR RESEARCH PHASE WERE INVOLVED IN SUBSEQUENT DRUG USE AND/OR OTHER CRIMINAL ACTIVITY TO AN EXTENT EQUAL TO THAT EXPERIENCED BY A CONTROL GROUP OF 109 PAROLEES WHO HAD RECEIVED NORMAL PAROLE SUPERVISION. AFTER HAVING BEEN OUT OF PRISON FOR AT LEAST 1 YEAR, ONLY 28 PERCENT OF THE EXPERIMENTAL GROUP AND 31 PERCENT OF THE CONTROL GROUP HAD NOT BEEN DETECTED USING DRUGS AND HAD NOT BEEN INCARCERATED FOR 90 DAYS OR MORE. THE ARTICLE EXAMINES THE PROGRAM DESIGN, THE HOUSE STRUCTURE AND LOCATION, AND VARIOUS PROGRAM COMPONENTS FOR THE PURPOSE OF DISCOVERING WHY THE PROGRAM FAILED. NO ONE FACTOR ADEQUATELY EXPLAINS THE PROGRAM'S FAILURE. THE RESENTMENT OF RESIDENTS, HOWEVER, REGARDING THEIR ASSIGNMENT TO THE FACILITY SEEMS TO HAVE BEEN AN IMPORTANT DETERRENT TO ITS SUCCESS. THE DECISION TO INCLUDE ONLY ADDICTS AMONG THE RESIDENTS APPEARS QUESTIONABLE, AS DOES THE DECISION TO INCLUDE ONLY MALES. IT IS SUGGESTED ALSO THAT MEXICAN-AMERICANS AS AN ADDICT OFFENDER GROUP PARTICULARLY MAY BE RESISTANT TO THIS TYPE OF PROGRAM. IN ADDITION, THE THERAPEUTIC VALUE OF THE HALFWAY HOUSE CONCEPT IS QUESTIONED. REFERENCES ARE INCLUDED. (MPK)