Three sets of clinical boundaries exist for posttraumatic stress disorder (PTSD), as for all concepts of psychiatric disorder. The first involves the border with normal psychology in general, and with the normal psychology of stress response in particular. This boundary can be surveyed from a number of vantage points and the maps which result will not necessarily correspond. The second boundary issue involves internal boundaries between psychiatric disorders, specifically between PTSD and other concepts of disorder. The high level of comorbidity documented in PTSD has ensured that this aspect of boundary setting is particularly contentious. The third set of boundaries is concerned with subtyping within the global construct of PTSD. The validity and extent of subtyping would be based on the degree to which phenomenological differences exist in relation to PTSD syndromes occurring in the wake of certain types of traumatic events. Such clinical subtyping might however need to be buttressed by external validity indicators such as differential treatment responses or outcome. A final boundary issue of major significance to therapists involves the need to place oneself unambiguously on the side of the trauma survivor in the struggle to resolve the traumatic experiences. The pivotal position of PTSD in the psychopathological arena is discussed.