The adjustment disorder (AD) diagnosis has clinical appeal to both doctors and patients. The idea of temporary emotional symptoms resulting directly from a stressful life event is viewed as a more normal human reaction than an idiopathic pathologic psychiatric state and is therefore less stigmatizing. Additionally, the disorder's more benign course (especially in adults) encourages a clinician to be more prognostically optimistic. This chapter discusses the prevalence, epidemiology, course and prognosis, and etiology of ADs. Also reviewed are AD subtypes proposed but not accepted for the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), including the acute stress disorder/posttraumatic stress disorder subtype and the bereavement-related subtype. Treatment options are covered, including psychotherapy, pharmacotherapy, and primary care. Tables outline diagnostic criteria for ADs in DSM-IV, stress-related disorders in DSM-5, DSM classifications, ADs in mental illness and medical settings, and subtypes of DSM-IV, text revision adjustment disorders. Graphs categorize patients diagnosed with ADs according to type of illness and the prognosis for recovery from ADs in adolescents and adults.This chapter contains 2 highly rendered figures, 6 tables, 109 references, and 5 MCQs.