THE UNIFIED DELINQUENCY INTERVENTION SERVICES (UDIS) PROGRAM BEGAN IN OCTOBER 1974; THE EVALUATION WAS CONDUCTED FROM APRIL 1976 TO SEPTEMBER 1977. UDIS' ULTIMATE OBJECTIVES ARE TO REDUCE DELINQUENCY AMONG CHICAGO AND SURROUNDING COOK COUNTY YOUTH AND TO REDUCE COMMITMENTS TO THE JUVENILE DIVISION OF THE DEPARTMENT OF CORRECTIONS (REFERRED TO AS DOC). IN ADDITION TO DEINSTITUTIONALIZING THE CHRONIC JUVENILE OFFENDER, OTHER FUNCTIONS OF UDIS ARE TO UNIFY RESOURCES AND TO GET THE YOUTH OUT OF THE JUVENILE JUSTICE SYSTEM FAST -- WITHIN 6 MONTHS IF POSSIBLE. A JUVENILE OFFENDER IS SAID TO BE ELIGIBLE FOR UDIS IF HE HAD BEEN ADJUDICATED DELINQUENT ON TWO PETITIONS OR IF HE HAD COMMITTED A SERIOUS OFFENSE AND, FOR EITHER REASON, WAS LIKELY TO BE COMMITTED TO DOC. YOUTHS ARE RECOMMENDED TO UDIS BY A PROBATION OFFICER, EVALUATED BY UDIS FOR ELIGIBILITY, REFERRED TO UDIS BY THE PROBATION OFFICER AT THE NEXT COURT HEARING, AND ASSESSED BY UDIS PSYCHOLOGISTS OR SOCIAL WORKERS IF THE JUDGE CONSENTS. A UDIS CASE MANAGER IS RESPONSIBLE FOR DEVELOPING A PROGRAM PLAN JOINTLY WITH THE YOUTH, HIS FAMILY, HIS PROBATION OFFICER, AND THE SERVICE AGENCIES. SERVICES PROVIDED UNDER UDIS INCLUDE ADVOCACY, COUNSELING, EDUCATIONAL/VOCATIONAL TRAINING, GROUP HOMES/FOSTER CARE, RURAL PROGRAMS (WILDERNESS PROGRAMS AND A WORK CAMP), AND INTENSIVE CARE (PSYCHIATRIC OR PSYCHOLOGICAL EVALUATION AND TREATMENT). THE EVALUATION OF UDIS INVOLVED COMPARING POLICE, COURT, AND INTERVENTION RECORDS FOR 191 MALE DELINQUENTS ASSIGNED TO UDIS, 159 MALE DELINQUENTS ASSIGNED TO THE DOC JUVENILE INSTITUTIONS DURING THE SAME TIME PERIOD, AND 142 MALE DELINQUENTS ASSIGNED TO THE DOC JUVENILE INSTITUTIONS DURING THE 21 MONTHS PRECEDING THE ESTABLISHMENT OF UDIS; IT WAS FOUND THAT, WHETHER THE PROGRAM WAS UDIS OR DOC, CORRECTIONAL INTERVENTION IN THE LIFE OF THE CHRONIC JUVENILE OFFENDER IN THIS STUDY HAD A POWERFUL AND APPARENTLY LONG-TERM INHIBITING EFFECT ON SUBSEQUENT DELINQUENT ACTIVITY. WHEN POSTINTERVENTION POLICE RATES OF THE COMBINED UDIS AND DOC SAMPLES WERE COMPARED TO THEIR POLICE RECORDS DURING THE YEAR PRECEDING INTERVENTION, IT WAS SEEN THAT ARRESTS DROPPED BY 67.8 PERCENT, COURT APPEARANCES DROPPED BY 64.4 PERCENT, VIOLENCE-RELATED OFFENSES DROPPED BY 73.7 PERCENT, AND AGGREGATE 'SERIOUSNESS' COSTS OF THE OFFENSES TO THE COMMUNITY DROPPED BY 65.2 PERCENT PER PERSON-MONTH (SIGNIFICANT AT THE .001 LEVEL). A 2-YEAR FOLLOWUP PERIOD SHOWED NO EVIDENCE OF A TENDENCY TO SLIP BACK INTO THE INITIAL DROP. THE RECIDIVISM ANALYSIS DID NOT MAKE A CASE FOR THE OVERALL SUPERIORITY OF EITHER UDIS OR DOC. DOC HAD AN EDGE IN REDUCING THE INCIDENCE OF OFFENSES; UDIS HAD AN EDGE IN REDUCING THE SERIOUSNESS OF THE OFFENSES THAT CONTINUED TO BE COMMITTED. RECOMMENDATIONS ARE OFFERED. APPENDIXES PRESENT THE DATA COLLECTION INSTRUMENTS, REFERENCES, AND SAMPLE OUTPUTS OF THE NORTHWESTERN UNIVERSITY SYSTEM FOR TRACKING UDIS CLIENTS. SUPPORTING DATA ARE PROVIDED. FOR AN EXECUTIVE SUMMARY OF THIS REPORT, SEE NCJ-45071.