Both inmates new to the jail environment and recidivists see jail as a dehumanizing situation characterized by toughness, routine order, and submission to authority. As a result, they become hostile to the jail staff and other inmates. The Inmate Recreational System Dynamics process is a positive indirect approach to relieve stress, depression, frustration, and idleness. The overall program is mandatory, but inmates have some freedom to select particular activities. In implementing the program, the Sacramento jail first hired experts to assess inmates' recreational needs and design a program, modified its indoor recreational areas, and purchased ping-pong tables, exercise equipment, video games, and table games. They instituted a standardized and a mandatory exercise routine at the beginning of each recreation period and published a monthly inmate newsletter. An outdoor recreation area allowed handball, weight lifting, speed bag and heavy bag workouts, and jogging. The program can serve as a reward and punishment tool and helps inmates adapt to the jail setting, maintain control over hostile and aggressive behavior, develop leisure-time skills, and maintain good physical condition. Diagrams and five references are supplied.