This study involved observing prisoner groups and their functions over 6 months as well as interviews with prisoner leaders, prison staff, and members of organizations that assist prisoner groups. Beginning with an ethnography of prisoner groups, the study aimed at identifying manifest and latent functions of various prisoner groups and the influence of the groups on prisoners, prison staff, and people in the community. Because of its psychological and physical deprivations, its coercive compliance structure, and its vulnerability to violence, the prison environment forces a prisoner to seek power and survival mechanisms. This inevitably involves some degree of participation in the inmate groups that compose the prison social system. Prisoners will most often seek membership in groups with their own ethnic identity. In CIM these prisoner social groups are not supported by most prison administrators and staff. Such a policy fails to recognize the important psychological support such groups provide inmates. Prisoner groups should be given resources, meeting spaces, permanent sponsors, freedom to make community contacts, and permission to have citizens in the community participate in group life in the prison. Even the prison gang should be accepted for its positive contributions to prisoner power and survival, although its crimes should not be condoned. The prison administrators should find creative ways to work with prisoner groups and organizations to help reduce violence and increase prosocial behavior among prisoners and between prisoners and staff. Appended are rules on inmate councils and committees and the Men's Advisory Council constitution and bylaws; a self-help group's constitution and bylaws; and memos, flyers, and letters relating to self-help group activities. About 100 bibliographic listings are provided.