The terrorist attacks on the Central London transport network on July 7, 2005, killed 52 commuters and caused approximately 700 injuries. Approximately 11 to 13 days after the London bombings 31% of Londoners reported one or more symptoms of substantial stress relating to the attacks. Although many of the psychological and behavioral repercussions of the July 7th attacks had diminished by the time of the seven-month follow-up, effects attributed to these attacks by respondents remained clearly observable. Personnel who plan disaster response require sufficiently robust data about the psychological consequences of major disasters, including terrorism, to move from doing what seems helpful to making management plans based on evidence. The July 7th bombing affected Londoners in a similar manner to other communities impacted by terrorism. A substantial minority were distressed in the initial weeks, and many months later only a small proportion continued to show signs of distress.