"The data was out there to warn us of this impending attack - why didn't we see it?" This question was heard again and again after the terrorist attacks on the World Trade Center and the Pentagon on September 11, 2001. Since then, statisticians have become an important part of the global war on terror. This book surveys emerging research at the intersection of national security and statistical sciences. In it, a diverse group of talented researchers address such topics as Syndromic Surveillance; Modeling and Simulation; Biometric Authentication; and Game Theory. The book includes general reviews of quantitative approaches to counterterrorism, for decision makers with policy backgrounds, as well as technical treatments of statistical issues that will appeal to quantitative researchers.