Transit systems -- subways, commuter railways, high-speed international trains, buses, and transport terminals -- offer attractive targets to terrorists throughout the world. The reasons for this include the difficulty of making transit facilities and vehicles secure and the large number of people who use transit systems. Police, transit operators, and emergency responders must consider the threat of transit terrorism when building their response capabilities. Although timely intelligence by police and government security agencies can prevent some acts, effective response capabilities are often the only tool available. Ongoing planning, training, exercises, and the development of a command-and-control capability that integrates planning/intelligence, operations, and logistics components into a cohesive response structure are essential. Such actions can save lives, mitigate the impact of transit terrorism, support investigative activities, and contribute to the rapid restoration of service. These capabilities, which integrate police and crisis transit response activities, can lead to effective incident management and reduce the attractiveness of transit targets, thus potentially reducing the threat against transit and preventing additional incidents.