The terrorist attacks of September 11, 2001, and the constant threat of imminent terrorist activity have brought into the forefront the urgent need to prepare for the consequences of such attacks. Such preparation entails utilization of existing knowledge, identification of crucial gaps in our scientific knowledge, and taking steps to acquire this knowledge. At present, there is little empirical knowledge about interventions following terrorism and absolutely no available empirical knowledge about interventions following bioterrorism. Therefore, this paper reviews knowledge about (1) reactions following the September 11 terrorist attacks in New York City and other places, (2) the practical experiences accumulated in recent years in countries (eg, Israel) that have had to cope with the threat of bioterrorism and the reality of terrorism, and (3) interventions for acute and chronic stress reactions following other types of traumatic events (eg, rape, war, accidents). Our review found several treatments efficacious in treating individuals for acute and chronic post-traumatic stress disorder (PTSD) related to other traumatic events that will likely be efficacious in treating PTSD related to terrorist attacks. However, there were significant gaps in our knowledge about how to prepare populations and individuals for the possibility of a terrorist attack and what interventions to apply in the immediate aftermath of such an attack. Accordingly, we conclude the paper with several questions designed to guide future research.