The authors focus on new threats -- biological attacks, "dirty bombs" containing radioactive materials, and "cyberattacks" that would disrupt the computer networks we rely on for communication, banking, and commerce -- and argue that US institutions must make fundamental changes to protect against them. They discuss not only the needed reorganization of government agencies but such institutional issues as establishing legal jurisdiction to respond to new threats, preparing health workers for attacks involving mass casualties, and equipping police, fire, and other emergency workers with interoperable communications systems. The final essays examine how Israel, Japan, and the United Kingdom have dealt with domestic terrorism, and what the United States can learn from their examples.