This article explores, according to Lazarus (1999) formulation, a cognitivist view of the Post-Traumatic Stress Disorder (PTSD) syndrome in conjunction with the transactional conceptualization of stress. The best models known in the behavioral and cognitive perspectives are reviewed to highlight the advantages of a transactional approach. The advanced rereading of PTSD provides a dynamic continuity view of the processes of adaptation to adversity, includes previous approaches and is consistent with the empirical results that have been obtained, also in Portugal.