This study aimed to test the dimensional structure of acute stress disorder (ASD). Latent profile analysis was conducted on scores from the Acute Stress Disorder Scale (Bryant, Moulds, & Guthrie, 2000) using a large sample of female victims of sexual trauma. Four distinct classes were found. Two of the classes represented high and low levels of ASD, and the high ASD class was associated with a high probability of subsequent posttraumatic stress disorder (PTSD). There were 2 intermediate classes that were differentiated by the number of arousal symptoms, and the class with high levels of arousal symptoms had a higher risk of PTSD. The results suggested that ASD is best described by qualitatively and quantitatively differing subgroups in this sample, whereas previous research has assumed ASD to be dimensional. This may explain the limited success of using ASD to predict subsequent PTSD. (PsycINFO Database Record (c) 2014 APA, all rights reserved).