Traumatic stress and its impact on the human experience have been recognized across a very wide range of cultures and historical eras. Descriptions of this psychological phenomenon can be found in literature as broad as Ulysses' Odyssey to the Koran and the Bible. The extant literature on trauma and post-traumatic stress disorder (PTSD) reviews four primary assessment methods: structured diagnostic interviews; self-report questionnaires; functional analytic clinical assessment; and psychophysio-logical assessment. The first step in assessing the impact of a potentially traumatic event is to identify the nature and specific details of the traumatic exposure, including assessing if it meets DSM-IV-TR 'traumatic event' criterion. Substance use disorders, mood disorders and other anxiety disorders are the most commonly occurring comorbid conditions with PTSD. It is important to remember that individuals with a trauma history may not be forthcoming about reporting the trauma in clinical settings.