This chapter highlights the two specific psychiatric manifestations of trauma, acute stress disorder (ASD) and its counterpart post-traumatic stress disorder (PTSD). It discusses management strategies for patients with ASD/PTSD in the emergency department (ED) and shows how the emergency physician (EP) can effectively identify the various presentations of PTSD, even when the symptoms are sub-threshold for a formal diagnosis. Symptoms of avoidance and re-experiencing are unique to PTSD and should help distinguish it from related anxiety disorders. The potential for clinically relevant physiologic manifestations of psychiatric stress is demonstrated by Takotsubo cardiomyopathy (TCM). In instances when the patient meets the diagnostic criteria for ASD/ PTSD, referral to outpatient psychiatric treatment is recommended. Such therapy may include psychopharmacology and cognitive behavioral, cognitive processing, or exposure therapy. In most practice settings, pharmacologic treatment should be initiated and managed outside of the ED by a primary care physician or mental health professional.