Contributions from 17 specialists based at hospitals and universities across the US summarize the findings on how extreme stressors such as war, sexual and other criminal victimization, natural and human-made disasters, and serious accidents affect physical health. The work outlines findings on trauma and post-traumatic stress disorder in relation to three domains: health status and disease, somatization, and utilization and costs. The contributors examine how trauma and PTSD can lead to poor physical health through correlates such as depression, hostility, and maladaptive coping and health behaviors. They also present findings on the biology of stress and implications for clinical and health policy.