The discussion of definition, presentation, and assessment sets out the criteria for PTSD, describes a model of the typical relationship between the three presenting symptoms, and summarizes the assessment of PTSD, exemplified by a case example. The cognitive-behavioral approach is introduced and applied to the treatment and counseling of patients with PTSD. Patients with acute PTSD exhibit symptoms lasting between 1 and 3 months, while chronic sufferers, who are usually more difficult to treat, present symptoms lasting longer than 3 months. Another condition, Prolonged Duress Stress Disorder, is experienced by patients who may suffer the indicative symptoms of PTSD without having experienced a single, overwhelming trauma. Counseling of patients with PTSD may be complicated with clients suffering concurrent anxiety and/or depression, or irritability. Issues related to service delivery include concurrent substance abuse, the efficacy of group counseling, childhood PTSD, and the relationship between childhood sexual abuse and adult PTSD. 48 figures, 90 references, and 4 appendixes