COST WERE ESTIMATED FROM A SAMPLE OF HALFWAY HOUSES SELECTED TO REPRESENT A CROSS SECTION OF HOUSES ACROSS THE U.S. FACTORS CONSIDERED WERE SIZE, TYPE, SERVICES PROVIDED, LOCATION, CLIENTS, AND AVAILABILITY OF COST DATA. ALL COST DATA WERE STANDARDIZED TO 1974 DOLLARS. FACILITY COSTS RANGED FROM $76 TO $1,391 PER BED PER YEAR. DAILY OPERATING COSTS RANGED FROM $4.77 TO $27.58 PER PERSON. MEAN FACILITY COST PER BED PER YEAR WAS $404; MEAN OPERATING COST WAS $13.55 DAILY. SOURCES OF COST VARIATION INCLUDED DIFFERENCES IN SERVICES PROVIDED, INTERREGIONAL PRICE VARIATIONS, RESOURCE AVAILABILITY, ECONOMICS OF SCALE, AND FACTOR INDIVISIBILITIES. AVERAGE DAILY CRIMINAL JUSTICE SYSTEM COSTS RANGED FROM $16.36 FOR BASIC IN-HOUSE SERVICES TO $22.05 FOR COMPREHENSIVE IN-HOUSE SERVICES. IN CONTRAST, THE AVERAGE ESTIMATED JAIL COST IS $19.29 PER INMATE PER DAY. EXTERNAL COSTS INCLUDED COLLEGE EDUCATION ($541 PER CLIENT YEAR); VOCATIONAL TRAINING ($900 PER CLIENT YEAR); DRUG TREATMENT ($1,278 TO $6,254 PER CLIENT YEAR); DETOXIFICATION ($15.84 TO $171.55 PER CLIENT DAY); AND MENTAL HEALTH ($23.63 TO $72.80 PER CLIENT DAY). CLIENTS' OPPORTUNITY COSTS DUE TO FOREGONE EMPLOYMENT AND LEISURE OPPORTUNITIES AND COMMUNITY COSTS (POTENTIAL TAX LOSS AND EFFECTS ON PROPERTY VALUES) ARE LARGELY UNQUANTIFIABLE. BOTH MACROECONOMIC AND MICROECONOMIC BENEFITS SHOULD ALSO BE CONSIDERED. ADDITIONAL RESEARCH ON SUCH TOPICS AS SHORT AND LONG-RUN FACILITY COSTS, EFFICIENT FACILITY DESIGN, SCALE ECONOMIES, AND BENEFITS TO HALFWAY HOUSES IS RECOMMENDED. TABLES AND A LIST OF THE HOUSES IN THE SAMPLE ARE INCLUDED. (CFW)