The process that resulted in the diagnostic criteria for posttraumatic stress disorder (PTSD) in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association; ) was empirically based and rigorous. There was a high threshold for any changes in any DSM-IV diagnostic criterion. The process is described in this article. The rationale is presented that led to the creation of the new chapter, "Trauma- and Stressor-Related Disorders," within the DSM-5 metastructure. Specific issues discussed about the DSM-5 PTSD criteria themselves include a broad versus narrow PTSD construct, the decisions regarding Criterion A, the evidence supporting other PTSD symptom clusters and specifiers, the addition of the dissociative and preschool subtypes, research on the new criteria from both Internet surveys and the DSM-5 field trials, the addition of PTSD subtypes, the noninclusion of complex PTSD, and comparisons between DSM-5 versus the World Health Association's forthcoming International Classification of Diseases (ICD-11) criteria for PTSD. The PTSD construct continues to evolve. In DSM-5, it has moved beyond a narrow fear-based anxiety disorder to include dysphoric/anhedonic and externalizing PTSD phenotypes. The dissociative subtype may open the way to a fresh approach to complex PTSD. The preschool subtype incorporates important developmental factors affecting the expression of PTSD in young children. Finally, the very different approaches taken by DSM-5 and ICD-11 should have a profound effect on future research and practice.