An estimated 80 to 90 percent of inmates in the Illinois corrections system have some affiliation with street gangs. The Illinois DOC considers itself at war with gangs and uses a multifaceted strategy of control and disruption. This account describes the DOC's cooperative efforts with other law enforcement agencies to identify gang members, methods for obtaining gang intelligence during the prison reception and evaluation process, and a computerized tracking system. Vigorous prosecution of violence within the prison is cited as a major weapon against gangs. Other tactics discussed are screening correctional officers to eliminate individuals who could be compromised, building staff skills to respond to gang-related activities, and educating the public and legislators. While the Illinois experience indicates there is no room for negotiating with gangs, legitimate channels of communication must be open to inmates. Consistent, common sense security is another important asset in fighting gangs.