Despite being developed before the formal introduction of posttraumatic stress disorder (PTSD) within the diagnostic literature, the Impact of Event Scale (Horowitz, Wilner, & Alvarez, 1979) remains one of the most widely used self-report measures of posttraumatic stress. This paper presents an overview of research using the IES in an attempt to assess its psychometric status. It is concluded that the psychometric properties of the IES are satisfactory (although not as a PTSD diagnostic measure) and that continued use of the IES as a measure of intrusive and avoidant processes is warranted.