1) The application of social identity theory and other social psychological and criminological theories to understanding youth association, affiliation, and disassociation with antisocial groups including street gangs and other delinquent groups. 2) The effects of community, official, program and family level "social control" responses on delinquent behavior and association with antisocial youth groups. 3) Evaluation of programs designed to reduce delinquent behavior and affiliation with street gangs.