Since the inception of posttraumatic stress disorder (PTSD) in the Diagnostic and Statistical Manual of Mental Disorders, third edition (DSM-III), there has been an ongoing polemic debate about the veracity, assessment, neurobiology, and longitudinal course of the disorder. As a consequence, its clinical utility has been the subject of a significant amount of conflicting opinion due to the competing interests involving clinicians, insurance companies, victim's groups, and governments. This article reviews some of the current divergent approaches in the diagnosis of PTSD, including the debate on the condition itself, claims that it is overdiagnosed, the usefulness of the “A” criterion, equivalence of cluster criteria, the role of combat and civilian PTSD, the role of biomarkers, incongruences in diagnostic practice, and the need for a consistent approach that ensures diagnostic congruence. Critical drivers of divergent diagnostic systems are that they should not produce significantly different rates or produce high levels of discordance. However, one of the concerns is that the anticipated International Statistical Classification of Diseases and Related Health Problems, eleventh edition (ICD-11) has moved away from this primary aim and taken a markedly divergent approach that is incompatible with the advancement of consensus within this critical field. This article explores some of the primary arguments and evidence cited for this approach in ICD-11 and recent changes in DSM-5. [Psychiatr Ann. 2016;46(9):498–509.]