This chapter reviews how disasters affect mental health globally, examines some key concepts for understanding the psychological impact of disasters, and concludes with a discussion of implications for policy, research, and field practitioners. The burden of mental illness on individuals, families, and communities following a disaster is substantial. Research on anxiety disorders in disasters has focused primarily around post-traumatic stress disorder (PTSD). Pre-disaster marginalized groups have limited access to health and relief services in the peri- and post-disaster time periods. Access to relief services can facilitate the return to normal mental health functioning. Ongoing stressors and trauma after a disaster also provide detail to the experience of psychopathology in post-disaster populations. Several theoretical models have been proposed to help explain how disasters affect population mental health. Recent research indicates that mental health practitioners are knowledgeable about different underlying constructs associated with the development of positive and deleterious mental health conditions.