Gang membership appears to facilitate increased involvement in violence and serious delinquency. In light of this, it is imperative to identify effective programs to reduce the level of gang membership and to reduce the impact that gang membership has in facilitating antisocial behaviors. Unfortunately there are no known gang intervention programs that meet current standards to be considered "evidence-based." There are, however, evidence-based programs (e.g., those identified by the Blueprints for Violence Prevention project) that have been shown to reduce violence, delinquency, and drug use. The Blueprints for Gang Prevention project is conducting a randomized controlled trial of a popular Blueprints model program, Functional Family Therapy, to ascertain its effectiveness in reducing gang membership and delinquency among youth at high risk of joining gangs and current gang members. The study is being conducted by Terence Thornberry and Denise Gottfredson in collaboration with the Functional Family Therapy national and local organizations in Philadelphia, researchers at Temple University, and the Philadelphia Family Court system. It is funded by the Office of Juvenile Justice and Delinquency Prevention and the Centers for Disease Control and Prevention.