THE 8.25 SQUARE MILES OF THE SPANISH-SPEAKING MARAVILLA AREA IN LOS ANGELES, CALIF., CONTAIN AT LEAST 14 ACTIVE GANGS REPRESENTING PERHAPS 3,500 PERSONS, BOTH ADULTS AND JUVENILES. OF THESE ABOUT 400 ARE 'HARDCORE' MEMBERS. THESE GANGS ARE LISTED ALONG WITH THEIR CHIEF CHARACTERISTICS. MANY DATE BACK TO THE 1920'S AND 1930'S. THE BASIC PSYCHOLOGICAL NEEDS WHICH THESE BARRIO GANGS MEET ARE EXAMINED--THE NEED TO BELONG, RECOGNITION, ACTIVITY, AND AN OPPORTUNITY TO DISPLAY MACHISMO OR MANHOOD. PAROLE OFFICERS ARE WARNED THAT THEY CANNOT WORK WITH A YOUNG MAN INDIVIDUALLY AND IGNORE THE POWERFUL PEER PRESSURES HE WILL FACE WHEN HE IS RELEASED INTO THE GANG ENVIRONMENT. TO ANSWER THE ARGUMENT THAT GANG ACTIVITY IS NOT THE PAROLE OFFICER'S BUSINESS, THE CIRCUMSTANCES SURROUNDING 27 MURDERS OR ATTEMPTED MURDERS ARE REVIEWED. A LARGE NUMBER OF THE VICTIMS WERE CALIFORNIA YOUTH AUTHORITY PAROLEES. THE FINAL PORTION OF THE PAPER COVERS DEVELOPING A RELATIONSHIP WITH THE COMMUNITY AND BEING ACCEPTED BY THE GANG MEMBERS. FOOTNOTES CONTAIN REFERENCES. (GLR)