Group interventions for survivors of trauma were first used following World War II with combat veterans struggling with the psychological consequences of their war experiences. Early groups were conducted months or years after combat, while the ensuing evolution of groups for trauma has diversified so that single-session groups are now often used to provide support for disaster survivors within the first few days or weeks after the event. From children in communities ravaged by hurricanes to female survivors of intimate partner violence, the types of trauma addressed by groups have also expanded. Reviews of studies on treatment outcome for group interventions for trauma/disaster reveal generally positive effects for group participation, regardless of the specific theoretical basis used by developers. Future research needs to identify variables that can be used to match participants to different group options for optimal outcomes.