THE 59 BOYS (AGES 14-20) SURVEYED WERE FORMER STUDENTS OF THE ZANDWIJK SCHOOL AND TREATMENT CENTER AND HAD LONG HISTORIES OF FAMILY PROBLEMS, CRIMINAL OFFENSES, AND NEUROSES. THE TREATMENT THEY RECEIVED INCLUDED INDIVIDUAL PSYCHOTHERAPY, GROUP AND FAMILY THERAPY, GENERAL EDUCATION, AND TUTORING. THE BOYS WERE COMPARED TO A STUDY GROUP OF 15 JUVENILE DELINQUENTS WHO HAD BEEN REFUSED BY THE SCHOOL DUE TO LACK OF SPACE. EXTENSIVE COMPARATIVE CRITERIA INCLUDED NUMBER OF OFFENSES AFTER TREATMENT, DEVELOPMENT IN STUDIES, PARTNER RELATIONSHIPS, SOCIAL CONTACTS, AND MENTAL HEALTH. THE ZANDWIJK GROUP COMPARED FAVORABLY IN TERMS OF MOST CRITERIA ALTHOUGH THE NUMBER OF OFFENSES WAS THE SAME FOR BOTH GROUPS. IN ORDER TO DETERMINE WHAT HAD CAUSED THE IMPROVEMENT, METHODS WERE DEVELOPED TO STATISTICALLY EVALUATE THE GENERAL EDUCATIONAL AND THE PSYCHOTHERAPEUTIC ASPECTS OF THE TREATMENT. WHILE THE IMPACT OF PSYCHOTHERAPEUTIC TREATMENT REMAINED INCONCLUSIVE, THE INFLUENCE OF THE GENERAL EDUCATIONAL EFFORTS PROVED TO BE SIGNIFICANT. BOYS HAVING SOCIAL AND PSYCHOLOGICAL ADJUSTMENT PROBLEMS RESPONDED BEST TO THE ZANDWIJK TREATMENT. THE STUDY CONTAINS NUMEROUS STATISTICAL CHARTS AND A SHORT BIBLIOGRAPHY. --IN FRENCH. (SAJ)