New theoretical models of mood and anxiety disorders have been proposed to better understand the relations and patterns leading to their high diagnostic comorbidities. These models have highlighted two new groupings of the disorders, focused on the prevalence of fear and distress symptoms. The present study investigated the fit of the symptoms of posttraumatic stress disorder (PTSD) in these new models. The relations between the two primary sets of symptom scales of PTSD and the diagnoses of other comorbid disorders were examined in a large multisite sample of veterans from primary care clinics. The results suggested that there was no reliable difference in the predictive power of any of the PTSD symptom scales across the two diagnostic groups. New transdiagnostic models, assessment practices, and treatment approaches may provide better understanding of symptom overlap and diagnostic comorbidity in PTSD and related disorders.