An exploration of the emotions of despair, fear and anger that arose after the terrorist attacks on the World Trade Center and the Pentagon in the autumn of 2001. The authors analyze reactions to the attacks through the lens of terror management theory, an existential psychological model that explains why humans react the way they do to the threat of death and how this reaction influences their post-threat cognition and emotion. The theory provides ways to understand and reduce terrorism's effect and possibly find resolutions to conflicts involving terrorism. The authors focus primarily on the reaction in the United States to the 9/11 attack, but their model is applicable to all instances of terrorism, and they expand their discussion to include the Israeli-Palestinian conflict. The work has practical implications and should be a useful resource for mental health practitioners, researchers, and anyone concerned with the causes and effects of terrorism.