Provides guidance for communities that are considering how best to address a youth gang problem that already exists or threatens to become a reality. The guidance is based on the Model developed through the Office of Juvenile Justice and Delinquency Prevention (OJJDP). This Report describes the research that produced the Model, notes essential findings from evaluations of several programs demonstrating the Model in a variety of environments, and outlines ¿best practices¿ obtained from practitioners with years of experience in planning, implementing, and overseeing the Model in their communities. Includes specific practices that work best in a step-by-step planning and implementation process for communities using the Model. Illus.