Post-traumatic stress disorder (PTSD) is a serious mental disorder that develops in some individuals following exposure to severe psychological stressors. In this chapter, we provide an overview of the conceptual issues, specific methods, and practical considerations in evidence-based assessment of PTSD. First, we outline the conceptual issues and practical components of a comprehensive assessment of PTSD. Second, we provide an overview of the most widely used self-rated and clinician-rated measures of trauma exposure and PTSD, comorbid disorders, and response bias. Third, we discuss cultural considerations in assessing PTSD. Fourth, we offer practical guidelines for conducting a clinically sensitive assessment of PTSD, highlighting some of the unique considerations in engaging trauma survivors in the assessment process and optimizing the information obtained. Last, we briefly summarize conceptual considerations and specific measures for other trauma- and stressor-related disorders.