This chapter reviews individual and community psychological and behavioral responses to two types of disaster with global reach: Weapons of mass destruction (WMD) used by terrorists; and pandemics, outbreaks of infectious disease which span the globe. Although there have been thousands of terrorist attacks throughout the world using conventional weapons, the use of WMD, in particular chemical and biological agents is a relatively new phenomenon. Behavioral responses to chemical, biological, radiological, nuclear (CBRN) agents represent several areas of special concern including the overwhelming of medical facilities, mass sociogenic illness, panic and responses of hospital staff and first responders. Mental health intervention is a prompt and effective medical response to a bioterrorism attack. SARS and avian influenza have brought worldwide attention to the possibility of a pandemic spreading across the globe. Mental health surveillance is important for directing services and funding.