This is a review of the relevant empirical literature concerning the DSM-IV-TR diagnostic criteria for PTSD. Most of this work has focused on Criteria A1 and A2, the two components of the A (Stressor) Criterion. With regard to A1, the review considers: (a) whether A1 is etiologically or temporally related to the PTSD symptoms; (b) whether it is possible to distinguish "traumatic" from "non-traumatic" stressors; and (c) whether A1 should be eliminated from DSM-5. Empirical literature regarding the utility of the A2 criterion indicates that there is little support for keeping the A2 criterion in DSM-5. The B (reexperiencing), C (avoidance/numbing) and D (hyperarousal) criteria are also reviewed. Confirmatory factor analyses suggest that the latent structure of PTSD appears to consist of four distinct symptom clusters rather than the three-cluster structure found in DSM-IV. It has also been shown that in addition to the fear-based symptoms emphasized in DSM-IV, traumatic exposure is also followed by dysphoric, anhedonic symptoms, aggressive/externalizing symptoms, guilt/shame symptoms, dissociative symptoms, and negative appraisals about oneself and the world. A new set of diagnostic criteria is proposed for DSM-5 that: (a) attempts to sharpen the A1 criterion; (b) eliminates the A2 criterion; (c) proposes four rather than three symptom clusters; and (d) expands the scope of the B-E criteria beyond a fear-based context. The final sections of this review consider: (a) partial/subsyndromal PTSD; (b) disorders of extreme stress not otherwise specified (DESNOS)/complex PTSD; (c) cross- cultural factors; (d) developmental factors; and (e) subtypes of PTSD.