A terrorist attack is an adverse event characterized by both an event-specific stressor and concern about future threats. Little is known about age differences in responses to terrorism. This longitudinal study examined generalized distress, posttraumatic stress responses, and fear of future attacks following the September 11, 2001 (9/11) terrorist attacks among a large U.S. national sample of adults (N = 2,240) aged 18-101 years. Individuals completed Web-based surveys up to 6 times over 3 years post 9/11. Multilevel models revealed different age-related patterns for distress, posttraumatic stress, and ongoing fear of future attacks. Specifically, older age was associated with lower overall levels of general distress, a steeper decline in posttraumatic stress over time, and less change in fear of future terrorist attacks over the 3 years. Understanding age differences in response to the stress of terrorism adds to the growing body of work on age differences in reactions to adversity. (Contains 4 tables, 3 figures and 3 footnotes.)