SUBJECTS OF THE HOME PROBATION STUDY WERE 507 YOUTHS PLACED ON PROBATION IN 1964 AND 1965. THE HOSTEL SAMPLE INCLUDES 4,346 PROBATIONERS WHO ENTERED HOSTELS BETWEEN 1954 AND 1963, AND 429 PROBATIONERS WHO ENTERED HOSTELS BETWEEN JULY 1960 AND JUNE 1961. BACKGROUND AND RECIDIVISM DATA FOR HOME AND HOSTEL PROBATION GROUPS ARE COMPARED, WITH A VIEW TO RELATING ENVIRONMENTAL FACTORS TO PERSONALITY DATA. THE ANALYSIS SHOWS THAT A PROBATIONER'S DELINQUENCY MAY DEPEND MARKEDLY ON HIS IMMEDIATE ENVIRONMENT, BE IT HOME OR HOSTEL. HOME PROBATIONERS FROM SOME TYPES OF FAMILY HAVE FAR HIGHER RECONVICTION RATES THAN OTHERS. RECONVICTION IS MORE COMMON FOR YOUTHS FROM CERTAIN TYPES OF HOSTEL REGIME THAN FOR OTHERS. IN BOTH THE FAMILY AND THE INSTITUTION, THE BEHAVIOR OF THE ADOLESCENT DELINQUENT APPEARS TO BE DETERMINED BY HIS NEED FOR A FIRM FATHER FIGURE WHOSE DISCIPLINE IS SUPPORTED BY THE MOTHER AND WHO IS NOT AFRAID OF EMOTIONAL INVOLVEMENT. THE MOTHER APPARENTLY IS IMPORTANT ONLY IN RELATION TO THE FATHER. THE INFLUENCE OF FAMILY CIRCUMSTANCES IS NOT THE SAME FOR ALL OFFENDERS IN EITHER SAMPLE. THE FINDINGS HAVE IMPLICATIONS FOR THE TYPOLOGIES USED TO CLASSIFY DELINQUENTS FOR TREATMENT, INDICATING THE SIGNIFICANCE OF THE IMMEDIATE HOME ENVIRONMENT AS A DIAGNOSTIC FACTOR. A SOCIAL WORK DIAGNOSIS MODEL THAT TAKES THE HOME ENVIRNONMENT INTO CONSIDERATION IS SUGGESTED. SUPPORTING DATA AND A LIST OF REFERENCES ARE INCLUDED. (IKM)