The authors' objective was to examine the ability of acute stress disorder (ASD) and other trauma-related factors in a group of physical assault victims in predicting post-traumatic stress disorder (PTSD) 6 months later. Subjects included 214 victims of violence who completed a questionnaire 1 to 2 weeks after the assault, with 128 participating in the follow-up. Measures included the Harvard Trauma Questionnaire, the Trauma Symptom Checklist, and the Crisis Support Scale. Twenty-two percent met the full PTSD diagnosis and 22% a subclinical PTSD diagnosis. Previous lifetime shock due to a traumatic event happening to someone close, threats during the assault, and dissociation explained 56% of PTSD variance. Inability to express feelings, hypervigilance, impairment, and hopelessness explained another 15% of PTSD variance. The dissociative, the reexperiencing, the avoidant, and the arousal criteria of the ASD diagnosis correctly classified 79% of the subsequent PTSD cases.