Two clear issues are raised by the question of when to assess dissociation in acute stress disorder. First, we want to maximize the likelihood of identifying individuals who will develop PTSD. Second, we want to minimize the likelihood of pathologizing "normal" transient stress reactions. The problems associated with defining dissociation in the context of an acute stress disorder diagnosis have been well reviewed (3, 4). Of relevance to our discussion is the problem that while three or more dissociative symptoms are required "either while experiencing or after experiencing the distressing event" (criterion B), criterion G requires the symptoms of acute stress disorder to last "for a minimum of 2 days." Depending on how this apparent contradiction is interpreted, the diagnostic criteria seem to imply the use of either peritraumatic or persistent dissociation in the diagnosis of acute stress disorder. An increasing body of literature is questioning the usefulness of peritraumatic dissociation in the prediction of PTSD (5, 6). Marshall and Schnell (5) also highlight the problems associated with the reliability of retrospective reporting of peritraumatic dissociation. Very few studies, however, have compared the predictive ability of peritraumatic versus persistent dissociation. In one of the few published studies, Murray et al. (7) found that persistent dissociation was a stronger predictor of chronic PTSD than peritraumatic dissociation. They argue that although initial dissociation may put individuals at risk for PTSD, many are able to compensate in the posttrauma period. However, those who continue to dissociate are at a high risk of later PTSD.