A three-group quasi-experimental design contrasted the responses of rescue workers to the 1989 Loma Prieta earthquake Interstate 880 freeway collapse (n = 198) with responses to critical incident exposure of Bay Area Controls (n = 140) and San Diego Controls (n = 101). The three groups were strikingly similar with respect to demographics and years of emergency service. The I-880 group reported higher exposure, greater immediate threat appraisal, and more sick days. The three groups did not differ on current symptoms. For the sample as a whole EMT/Paramedics reported higher peritraumatic dissociation compared with Police. EMT/Paramedics and California road workers reported higher symptoms compared with Police and Fire personnel. Nine percent of the sample were characterized as having symptom levels typical of psychiatric outpatients. Compared with lower distress responders, those with greater distress reported greater exposure, greater peritraumatic emotional distress, greater peritraumatic dissociation, greater perceived threat, and less preparation for the critical incident.