Some 28 researchers collected data in 17 States from 85 correctional facilities (prisons, jails, boot camps, juvenile detention centers, juvenile correctional institutions, etc.). The national sample included about 10,000 confined offenders, of whom approximately 4,000 were self-reported gang members. A comparison of gang members and non-gang members showed a number of significant differences. Gang members tended to be more predatory and more violent, both inside and outside of correctional facilities. Gang members tended to be less deterred by the possibility of stiffer sanctions. Hispanic/Latino/Mexican American inmates had the highest density of gang membership compared with other racial/ethnic groups. Among the findings on gang life in modern America were that the average age for joining a gang, nationally, was 12.8 years old. More than half of the gang members had held some rank or leadership position in their gang. More than half reported that their gang has a special language, and more than two-thirds said their gang has written rules for its members. Most gangs are adult-driven gangs with older adult leaders who have been in the gang for many years. Also included in this executive summary are a discussion of the development of a security threat group/gang classification system, findings on female gang members, a comparison of juvenile and adult gang members, gang organization and its impact on gang behavior, and family dysfunction as a factor in explaining gang member behavior. The report recommends that the Uniform Crime Reporting system be modified to indicate whether an arrestee is a gang member, and if "yes," the name of the gang.