This chapter describes the interface of mental health and disaster. The burden of mental illness for families, communities, and nations is substantial, and the mental illness that follows extreme traumatic events is part of this global burden. Accurate and real-time health surveillance information on the population rates of mental health and illness and the barriers to care are needed to address the mental and behavioral health-care needs of disaster populations. The chapter discusses the range of psychological and behavioral responses to disaster, from subsyndromal symptoms of distress, to initial behavior, distress and health risk behaviors, to the development of specific psychiatric disorders. Cognitive-behavioral psychotherapeutic interventions for children and adults with complex grief are under investigation. The chapter focuses on the complexity of modeling psychopathology after disaster-posttraumatic stress disorder (PTSD). The conceptualization of postdisaster pathology and PTSD requires a broader view across domains of suffering, altered functional capacity, and disability.