While overcrowding, idleness, and tight security restrictions contribute to a stressful prison environment, they do not always produce collective violence. Each of these factors is made more salient by a heterogeneous inmate population which finds the search for a satisfying living strategy less easy. The same conditions also frustrate guards' efforts to create work environments compatible with their needs and develop relationships with prisoners that can reduce stress. Officers react to changing conditions and perceived administrative interference by altering work styles and varying previously predictable responses, thus contributing to inmate stress. As prison conditions change due to crowding, increased security, and an influx of hetereogeneous inmates, both prisoners and guards lose their abilities to determine their own reality. Relationships become more formalized, and confrontations between guards and inmates increase, setting the stage for riots. While violence is a way of life in prison, restraints on overt violence must be reduced and justification for collective violence put into place. The status quo is a powerful restraint, along with concern for personal safety, fear of arrest, and a commitment to orderly social change. However, under conditions of change and danger, disciplinary procedures may become meaningless. Six conditions contribute to an individual's justifying the use of collective violence: denying the victims' humanity, organizational goals superceding individual goals, loyalty to the organization superceding all other considerations, an organization using secrecy and isolation to cover its actions, the existence of a target population, and a motivation to engage in violence. The paper provides 2 footnotes and 27 references.