Little is known about the variables that might be associated with posttraumatic stress symptomatology in high-risk occupational groups such as professional firefighters and paramedics. A sample of 173 urban professional firefighter/EMT's and firefighter/paramedics rated and ranked the stressfulness of 33 actual and/or potential duty-related incident stressors. They also reported whether they had experienced each of these incident stressors within the past 6 months and, if they had, to recall on how many occasions within the past 6 months. A principal components analysis of their rescaled incident stressor ratings yielded five components: Catastrophic Injury to Self or Co-worker, Gruesome Victim Incidents, Render Aid to Seriously Injured, Vulnerable Victims, Minor Injury to Self and Death & Dying Exposure.