PTSD was measured using the Civilian Mississippi scale, while traumatic stressors were assessed using a traumatic stress schedule designed to collect data on past traumatic events. Four social support measures were used: emotional support from peers, supervisors, and nonwork sources; content of communication with supervisors and peers; ease of talking about trauma at work; and attitudes toward expressing emotion at work. The prediction that lower social support would be related to higher PTSD scores was supported for social support from peers, supervisors, and outside work but not for negatively expressed support. The prediction that these aspects of social support would interact with traumatic experiences was supported for attitudes toward expressing emotion at work. Findings suggest there are important types of ongoing social support, from peers in particular, that can be fostered or provided for by organizations. 54 references, 4 tables, and 1 figure