The resource manual is divided into two parts with each reflecting a particular perspective on youth gang membership in juvenile detention centers. Part 1 looks at the research, including quantitative and qualitative assessments. An overview of the problem of youth gangs in detention facilities is presented, as well as findings from the National Juvenile Detention Association's national survey of detention centers and correctional facilities which assessed the nature and extent of youth gang problems in detention centers and correctional facilities, assessed the use of risk and needs assessment instruments for security classification and matching gang members with programs, and identified promising and effective programs. Five lessons learned set forth by the National Juvenile Detention Association (NJDA) are presented. Part 2 examines successful practices and includes case study materials supplying practical strategies to address the operational challenges, such as a classification system. Three facility-based programs were chosen based on results of a survey and substantiation of program effectiveness (Shuman Detention Center, Pittsburgh, PA; Santa Cruz Juvenile Hall, Santa Cruz, CA; and Duval Regional Juvenile Detention Center, Jacksonville, FL). An a detailed description is presented of how Santa Cruz County Probation officials developed a juvenile detention program integrating opposing gang members, resulting in a safer environment for residents and staff. This two-part manual is a first step to address systematically the effective operation of juvenile detention in light of the youth gang membership phenomenon. Tables, references, and appendixes