Groups of people who have been victims of intense persecution, violence, mass killings, and genocide are deeply affected. This is true, of course, of individual survivors of mass killings or genocides, who were in camps or in territories where the violence occurred and who were personally targeted as victims. But it is also true of members of the victim group who were not in direct danger. They are also deeply affected by the persecution and the attempt to eliminate all or part of their group.

For most people, individual identity is deeply rooted in their group identity (Bar-Tal & Staub, 1997; Staub, 1997a), especially in the case of racial, ethnic, and even religious groups, with membership in the group often not experienced as a matter of choice. The deaths of many others belonging to the group, the knowledge that, except for circumstances (often accidental ones like geography), one would have been killed, and the effects of the genocide on the whole group have deep impact on individuals, ranging from survivor guilt, to devaluation of oneself and one's group, to insecurity and the perception of the world as hostile.

Past victimization affects people's assumptions about the world (Janoff-Bulman, 1992). It deeply frustrates basic human needs like the need for security, for a positive identity, for a sense of effectiveness and control, for positive connections to others, and for a usable, meaningful comprehension of reality, including one's own place and role in the world (Staub, 1989, 1996).