THIS STUDY WAS INTENDED TO EXTEND PREVIOUS FINDINGS THAT JUVENILE DELINQUENTS TREATED ACCORDING TO THE INTERPERSONAL MATURITY LEVEL CLASSIFICATION SYSTEM (I-LEVEL) SHOW IMPROVED PROBATION OUTCOME. THE RATIONALE FOR THE PRESENT RESEARCH IS THE PREDICTION THAT PROBATION OUTCOME FOR JUVENILES IS ENHANCED BY THE FOLLOWING SEQUENTIAL SET OF OPERATIONS: (A) THE DIFFERENTIAL CLASSIFICATION OF OFFENDERS AS TO THE MEANING OF THEIR CRIME (IN PSYCHOGENIC TERMS); (B) THE MATCHING OF WORKER STYLES OF PROBATION OFFICERS WITH THE CLASSIFICATION OF THE JUVENILE; AND (C) THE USE OF THE I-LEVEL TREATMENT PROGRAM WHICH INVOLVES TREATING THE VARIOUS DELINQUENT SUBTYPES DIFFERENTLY. THE STUDY FOCUSED ON THREE DEPENDENT MEASURES OF PROBATION OUTCOME; NAMELY, DECREASE IN RECIDIVISM, CHANGE IN SELF CONCEPT SCORE AND STABILITY AS MEASURED BY SCHOOL OR WORK ATTENDANCE. FORTY-EIGHT JUVENILE PROBATIONERS WERE RANDOMLY ASSIGNED TO I-LEVEL TREATMENT, ALTERNATE TREATMENT, AND MINIMAL SUPERVISION. THE STUDY EXAMINED THE EFFECTS OF SIX MONTHS OF PROBATION SUPERVISION ON SELF CONCEPT, WORK STABILITY, AND SCHOOL STABILITY. THE EFFECTS OF PROBATION ON RECIDIVISM WERE EXAMINED FOR A 12 MONTH PERIOD. THE DATA SUGGESTED THAT I-LEVEL TREATMENT OUTPERFORMED THE OTHER TWO GROUPS ON THE DEPENDENT MEASURES OF INCREASED SELF-CONCEPT, DELINQUENCY REDUCTION, AND STABILITY IN SCHOOL OR WORK ATTENDANCE. (AUTHOR ABSTRACT MODIFIED)