This chapter presents key assessment issues and recommendations to assist in patient selection and examination of response across the prolonged exposure-intensive outpatient (PE-IOP) treatment program. The authors discuss key issues including dissociation, suicide and self-harm risk, anger, moral injury, complex trauma, personality disorder, guilt, and comorbidity. Specific patient populations are discussed, including military, sexual assault, and traumatic brain injury populations. Discussion of a process for screening, assessment, and treatment planning using an interdisciplinary treatment team is presented.