Personnel of the U.S. Army Center for Health Promotion and Preventive Medicine responded to the September 11, 2001 terrorist attack on the Pentagon with in a multipronged approach that encompassed the areas of environmental science, behavioral health, occupational and preventive medicine, risk communication, epidemiology, and medical surveillance. In the early weeks and months following the attack the USACH-PPM staff: completed an in-depth environmental exposure assessment of the Pentagon; assisted the North Atlantic Regional Medical Command in providing direct health care to those with physical and mental health concerns; have developed, fielded, processed, and are analyzing the results of the Pentagon Post-Disaster Health Assessment; and have returned information on these areas to both decision makers in Department of Defense and the employees of the Pentagon.