THE EVALUATION ENCOMPASSES THREE ADULT HALFWAY HOUSES OPERATED BY REHABILITATION MENTAL HEALTH SERVICES, INC., SANTA CLARA COUNTY, CALIF. THE EVALUATION REPORT OPENS WITH REVIEWS OF THE HALFWAY HOUSE MOVEMENT, PREVIOUS STUDIES OF HALFWAY HOUSES, AND THE APPLICATION OF THE REHABILITATION MODEL IN HALFWAY HOUSES. DETAILS OF THE DESIGN AND METHODS OF THE SANTA CLARA EVALUATION ARE PRESENTED, FINDINGS ARE REPORTED, AND RECOMMENDATIONS FOR HALFWAY HOUSE PLANNING AND RESEARCH ARE OFFERED. THE EVALUATION INVOLVED OBTAINING FUNCTIONAL RATING SCORES FOR PERSONS ADMITTED TO AND DISCHARGED FROM THE THREE PROGRAMS FROM JULY THROUGH DECEMBER 1973 AND FOR PERSONS WHO HAD BEEN DISCHARGED FROM THE PROGRAM APPROXIMATELY 6 MONTHS PRIOR TO THE STUDY. THE MOST SUPRISING FINDING WAS THAT THE GREATEST CHANGE IN FUNCTIONAL RATING SCORES TOOK PLACE IN THE POSTRESIDENCY PERIOD. NUMBER AND DURATION OF PREVIOUS HOSPITALIZATIONS APPEAR TO BE RELATED TO LENGTH OF STAY IN THE HALFWAY HOUSE FACILITY. HALFWAY HOUSE RESIDENCY IMPROVED THE RATE OF EMPLOYMENT FOR PERSONS PREVIOUSLY HOSPITALIZED FOR PSYCHIATRIC REASONS. IMPLICATIONS OF THESE AND OTHER FINDINGS ARE DISCUSSED, TOGETHER WITH PROBLEMS ENCOUNTERED IN IMPLEMENTING THE RESEARCH. SUPPORTING DATA, COPIES OF STUDY INSTRUMENTS, AND A BIBLIOGRAPHY ARE INCLUDED. (LKM)