This study identified predictors of symptomatic distress in emergency services (EMS) personnel exposed to traumatic critical incidents. A replication was performed in 2 groups: 154 EMS workers involved in the 1989 Interstate 880 freeway collapse during the San Francisco Bay area earthquake, and 213 counterparts from the Bay area and from San Diego. Evaluated predictors included exposure, social support, and psychological traits. Replicated analyses showed that levels of symptomatic distress were positively related to the degree of exposure to the critical incident. Level of adjustment was also related to symptomatic distress. After exposure, adjustment, social support, years of experience on the job, and locus of control were controlled, 2 dissociative variables remained strongly predictive of symptomatic response. The study strengthens the literature linking dissociative tendencies and experiences to distress from exposure to traumatic stressors.