This study investigated the association of 15 exposures, 10 stressors, and 18 life events with illness symptoms reported by 978 veterans who believe they suffer from Gulf War-related illnesses. The data suggested that belief in CBW exposure, and the experience of war stress and serious negative life events after the war, are important concomitants of Gulf War illness. Models seeking to explain Gulf War symptoms need to incorporate a range of exposure and psychosocial factors to fully account for important influences.