THE CITIES STUDIED INCLUDE NEW YORK, LOS ANGELES, CHICAGO, PHILADELPHIA, DETROIT, AND SAN FRANCISCO. OF PARTICULAR INTEREST WERE MORE FORMALLY ORGANIZED GANGS WITH IDENTIFIABLE LEADERSHIP, LINES OF AUTHORITY, CONTINUING INTERACTION AMONG MEMBERS, SPECIFIC TERRITORIAL DOMAIN, AND RECURRENT INVOLVEMENT WITH VIOLENT OR ILLEGAL BEHAVIOR. ESTIMATES OF THE NUMBER OF GANGS AND THEIR MEMBERSHIPS WERE FOUND TO VARY WIDELY WITHIN EACH CITY. A TABLE SHOWING HIGH AND LOW ESTIMATES AND ESTIMATED RACIAL/ETHNIC COMPOSITIONS OF GANGS IS PRESENTED. FOR EXAMPLE, IN LOS ANGELES, ESTIMATES OF THE NUMBER OF GANGS RANGE FROM 160 TO MORE THAN 1,000; AND IN PHILADELPHIA ESTIMATES OF GANG MEMBERSHIP RANGE FROM 4,700 TO 15,000. THE GREAT MAJORITY OF GANG MEMBERS ARE MALES BETWEEN 10 AND 21 YEARS OF AGE, GENERALLY OF LOW SOCIOECONOMIC STATUS. ALTHOUGH INCREASES IN FEMALE GANG MEMBERSHIP WERE FREQUENTLY NOTED, LITTLE FIRM EVIDENCE FOR THIS WAS FOUND. ARRESTS OF FEMALE GANG MEMBERS ARE UNCOMMON, AND WHERE SUCH GANGS EXIST, THEY ARE USUALLY AUXILIARY BRANCHES OF AN ESTABLISHED MALE GANG. MOST GANG ACTIVITY IS STILL BASED IN URBAN GHETTO AREAS, AND ETHNIC RACIAL COMPOSITIONS TEND TO REFLECT SHIFTING POPULATIONS IN THESE AREAS. INTERGANG WARFARE GENERALLY INVOLVES GUERRILLA TACTICS, AND MOST RAIDING PARTIES ARE ARMED WITH HANDGUNS, SHOTGUNS, AND RIFLES. GANGS CAUSE CONSIDERABLE DAMAGE TO LOCAL PROPERTY, AND GANG ACTIVITY IN THE SCHOOLS POSES A SERIOUS THREAT TO TEACHERS, STUDENTS, AND PROPERTY. AS A RESULT OF VIOLENCE AND EXTORTION, MANY SCHOOLS HAVE HAD TO HIRE PRIVATE POLICE AND SECURITY GUARDS. WHILE 60 PERCENT OF THE VICTIMS OF GANG VIOLENCE ARE OTHER GANG MEMBERS, THE REMAINING 40 PERCENT ARE LOCAL RESIDENTS PARTICULARLY THE ELDERLY, WOMEN, AND CHILDREN. INCREASING AVAILABILITY AND UTILIZATION OF FIREARMS BY GANG MEMBERS MAKES SUCH VIOLENCE INCREASINGLY LETHAL. URBAN DEMOGRAPHIC TRENDS MAKE IT LIKELY THAT THE MALE, POOR, IMMIGRANT POOL FROM WHICH GANGS DRAW THEIR MEMBERS WILL BE INCREASING IN THE NEXT 5 TO 10 YEARS. ONE OF THE MOST POPULAR EXPLANATIONS FOR THE EXISTENCE OF YOUTH GANGS IS THAT THE MEMBERS ARE PRODUCTS OF BROKEN, FATHERLESS HOMES. THE OUTLOOK FOR THE FUTURE IS GRIM; OVER HALF OF THOSE SURVEYED FELT GANG ACTIVITY WOULD BE INCREASING. WHILE SOME SUGGESTED THE INTRODUCTION OF TOUGHER POLICE POLICIES AND INTENSIVE SURVEILLANCE, OTHERS ASSERTED THAT SUCH TACTICS WOULD ONLY SOLIDIFY GANGS AND INCREASE VIOLENCE. (JAP)