As the first network of its kind in the Nation, the California Cities Gang Prevention Network brings together teams of municipal leaders, law enforcement officials, school district and community partners, and a host of other stakeholders who represent the public, private, and nonprofit sectors. The network has found that adherence to six core principles significantly increases the effectiveness of local gang-prevention work. First, the mayor and police chief must cooperate in providing leadership for gang-prevention efforts. Such leadership promotes the commitment to preventing gang-related violence and the development and implementation of a conceptual plan to prevent gang violence. Second, the prevention strategy must involve a balanced effort of law enforcement and social services, so as to ensure certainty of both consequences and help. Third, a comprehensive, citywide strategy must be developed. Fourth, an entity must be designated or created to track the work once the plan is developed and is in the process of being implemented. This will involve holding people accountable for fulfilling their responsibilities and altering the plan to improve performance. Fifth, municipal officials must forge a working and policymaking relationship with the county. County agencies have many of the resources of personnel and funding needed to impact local conditions. Sixth, the effort and the people involved in it must interact with youth in the community to give them a sense that caring adults in the community want to help in providing the friendships and resources needed for youth to have positive experiences and development. This toolkit provides guidance and resources for achieving the aforementioned six goals. Appended key contacts and resources, a bibliography, and sample gang-prevention collaborative