Acute stress disorder (ASD) is a poorly understood and controversial diagnosis (A. G. Harvey & R. A. Bryant, 2002). The present study used confirmatory factor analysis (CFA) to test the factor structure of the most widely used self-report measure of ASD, the Acute Stress Disorder Scale (R. A. Bryant, M. L. Moulds, & R. M. Guthrie, 2000), in a sample of Hurricane Katrina evacuees relocated to a Red Cross emergency shelter in Austin, Texas. Results indicated that the proposed 4-factor structure did not fit the data well. However, an alternate 2-factor model did fit the data well. This model included a second-order Distress factor (onto which the Reexperiencing, Arousal, and Avoidance factors loaded strongly) that was positively correlated with the Dissociation factor. Implications for the ASD construct and its measurement are discussed. (Contains 3 figures, 1 table and 3 footnotes.)