THERE WERE 536 SUBJECTS IN THIS STUDY; OF THESE 61 PERCENT WERE BLACKS AND 39 PERCENT WERE WHITE. EXTENSIVE TESTS AND QUESTIONNAIRES WERE USED TO GATHER DATA ON THE SUBJECTS. IN ADDITION, TRACES WERE CONDUCTED OF POLICE AND COURT RECORDS TO PROVIDE INFORMATION ON THE SUBJECTS' PAST CRIMINAL HISTORY. AMONG THE TYPES OF FACTORS STUDIED WERE SELF REPORTS OF DELINQUENT BEHAVIOR, FAMILY STRUCTURE AND HISTORY, FAMILY DYNAMICS, SCHOLASTIC MEASURES, VOCATIONAL HISTORY AND ASPIRATIONS, EMOTIONAL DISTURBANCES, AND ATTITUDES. THESE MULTIPLE FACTORS WERE COMBINED WITHIN A SINGLE COMPARATIVE PROCEDURE OF ANALYSIS. THE STUDY REVEALED THAT THE MOST POWERFUL SINGLE CHARACTERISTIC OF THE STREET GANG MEMBER WAS A HIGH PROCLIVITY FOR VIOLENCE. THE SECOND MOST POWERFUL FACTOR TO EMERGE WAS THE NUMBER OF ADVANTAGES THAT THE SUBJECT CITED AS BEING PROVIDED BY GANG MEMBERSHIP. OTHER VERY IMPORTANT FACTORS WERE DEFIANCE OF PARENTS, MORE POLICE ARRESTS FOR NONVIOLENT CRIMES, MORE TRUANCY EPISODES, ALCOHOL AND DRUG ABUSE, AND UNREALISTIC EXPECTATIONS OF SUCCESS. (AUTHOR ABSTRACT MODIFIED)