Recent cognitive models of trauma response predict that negative trauma appraisals are central to the development of psychopathological stress reactions. Fifty-nine civilian survivors of motor vehicle accidents (MVA; n = 24) and nonsexual assaults (n = 35) were assessed within 4 weeks of their traumatic event for acute stress disorder (ASD), prior traumatic events and prior mental health contact, and were administered the Anxiety Sensitivity Index and the Posttraumatic Cognitions Inventory. Participants who were diagnosed with ASD displayed more maladaptive appraisals about their functioning following their trauma and reported higher levels of concern regarding anxiety symptoms than those who were not diagnosed with ASD. Negative beliefs were strongly associated with acute stress severity. These findings are discussed in the context of cognitive mechanisms that may influence maladaptive adjustment following trauma.