A STUDY OF 1000 MALE OFFENDERS BORN IN 1949 AND LIVING IN LARGE CITIES, SMALL TOWNS, AND VILLAGES IN POLAND WAS CONDUCTED IN 1972. THE RESULTS SHOWED THAT THE SUBJECTS FROM THE RURAL AREAS BECAME FIRST OFFENDERS AT A LATER AGE; THEIR SYMPTOMS OF SOCIAL MALADJUSTMENT WERE LESS SEVERE, AND THEY COMMITTED OFFENSES AFTER REACHING ADULTHOOD LESS OFTEN THAN THE SUBJECTS FROM URBAN AREAS. FURTHERMORE, MEDIUM-SIZED CITIES (WITH 500,000 TO 100,000 INHABITANTS) HAD HIGHER NUMBERS OF JUVENILE OFFENDERS, AND MORE SOCIALLY MALADJUSTED ADULT OFFENDERS WHO USED TO BE JUVENILE DELINQUENTS THAN EITHER RURAL AREAS ON THE LARGE CITIES. THEREFORE, PREVENTIVE EFFORTS SHOULD BE DIRECTED IN GREATER DEGREE TO THE MEDIUM-SIZED CITIES, RATHER THAN ONLY TO THE LARGE CITIES. ALSO, CRIME PREVENTION WAS CONSIDERED AN URGENT PROBLEM IN VIEW OF THE DIMINISHING DIFFERENCES BETWEEN URBAN AND RURAL AREAS IN POLAND. THE STUDY ALSO SHOWED THAT AMONG THE CONVICTED YOUNG ADULTS (17 TO 22 YEARS OLD), MORE THAN ONE FIFTH WERE FORMER JUVENILE DELINQUENTS (UNDER 17 YEARS OLD). IT WAS ALSO NOTED THAT OF THE EFFORTS TO PREVENT JUVENILE CRIME, THE MOST EFFICENT WERE METHODS IN WHICH CONTACT WITH THE PENAL SYSTEM WAS AVOIDED. AS MANY AS 80 PERCENT OF THE BOYS WHO WERE PUT BY THE COURTS INTO JUVENILE CORRECTIONAL INSTITUTIONS SUBSEQUENTLY RETURNED TO CRIME. DESCRIPTION OF INDIVIDUAL CASES, REFERENCES, AND TABULAR DATA ARE INCLUDED.--IN POLISH.