In the DSM-5, the diagnosis of posttraumatic stress disorder (PTSD) has undergone multiple, albeit minor, changes. These changes include shifting PTSD placement from within the anxiety disorders into a new category of traumatic and stressor-related disorders, alterations in the definition of a traumatic event, shifting of the symptom cluster structure from three to four clusters, the addition of new symptoms including persistent negative beliefs and expectations about oneself or the world, persistent distorted blame of self or others, persistent negative trauma-related emotions, and risky or reckless behaviors, and the addition of a dissociative specifier. The evidence or lack thereof behind each of these changes is briefly reviewed. These changes, although not likely to change overall prevalence, have the potential to increase the heterogeneity of individuals receiving a PTSD diagnosis both by altering what qualifies as a traumatic event and by adding symptoms commonly occurring in other disorders such as depression, borderline personality disorder, and dissociative disorders. Legal implications of these changes include continued confusion regarding what constitutes a traumatic stressor, difficulties with differential diagnosis, increased ease in malingering, and improper linking of symptoms to causes of behavior. These PTSD changes are discussed within the broader context of DSM reliability and validity concerns.