A YOUTH RECREATIONAL PROGRAM WAS INITIATED AND OPERATED BY THE POLICE IN SKARHOLMEN, A STOCKHOLM SUBURB OF ABOUT 30,000 INHABITANTS. PARTICIPANTS WERE RECRUITED DURING THE FALL OF 1974. THE PROJECT WAS EVALUATED FROM THAT TIME UNTIL JUNE 30, 1975. NINE GROUPS INVOLVED IN VARIOUS RECREATIONAL ACTIVITIES WERE FORMED. TWO OF THE GROUPS WERE COMPOSED OF JUVENILES WITH A HIGH RISK OF CRIMINALITY RECRUITED FROM JUVENILES REGISTERED WITH THE POLICE-CHILD WELFARE BOARD OR CONSIDERED 'DIFFICULT' IN SCHOOL. THE OTHER GROUPS WERE RECRUITED THROUGH INFORMATION FROM THE SCHOOLS AND PARENTS. A TOTAL OF 221 YOUTHS PARTICIPATED, OF WHOM 17 WERE GIRLS. MOST (79 PERCENT) WERE BETWEEN THE AGES OF 10 AND 14, WITH NONE OLDER THAN 16 YEARS. PARTICIPANTS WERE DIVIDED INTO 3 GROUPS ACCORDING TO DEGREE OF PARTICIPATION: AN INTENSIVE GROUP (PARTICIPATED AT LEAST 20 TIMES), AN AVERAGE GROUP (PARTICIPATED 3-19 TIMES), AND AN INACTIVE GROUP (PARTICIPATED 1-2 TIMES). TO EVALUATE THE CRIME PREVENTIVE EFFECT OF THE PROGRAM, THE REGISTERED MISBEHAVIOR OF PARTICIPANTS WAS EXAMINED BEFORE AND DURING THE EVALUATION-PARTICIPATION PERIOD. OF THE 221 YOUTHS, 16 CHANGED THEIR STATUS, 9 IMPROVED AND 7 DETERIORATED. THE LACK OF A CONTROL GROUP AND THE ABSENCE OF RANDOM RECRUITMENT WEAKENED THE EVALUATION RESULTS. THE GREATEST POSITIVE PROGRAM IMPACT WAS EXPERIENCED BY YOUNG PARTICIPANTS (UP TO 13 YEARS), THOSE WHO PARTICIPATED OFTEN, AND IN GROUPS WITH A SMALLER NUMBER OF PROBLEM BOYS. TABULAR DATA ARE INCLUDED. (RCB)