The Los Angeles Mayor’s Gang Reduction and Youth Development (GRYD) program works to reduce gang violence by providing prevention and intervention services concentrated in 12 zones. The fourth year of the GRYD evaluation examined program dosage, client and family experiences, program impact on youth risk factors for joining a gang, and community-level impacts on gang crime and violence. GRYD engaged youth with serious risk factors in intensive programming, and risk factors for GRYD Prevention clients declined. There was mixed evidence regarding whether the GRYD Zones “outperformed” comparison areas in reducing gang violence and crime.