Through innovative analysis, discussion, and historical examples, the book argues that an unconventional threat does not just consist of terrorism, but also includes sabotage and subversion. It describes different pathways to becoming a terrorist, including those illuminated by the rational actor, psychological, social identity, and organizational approaches to understanding terrorism. The book also features discussion of possible sabotage through the Internet. The book is an excellent text for upper division undergraduate and Master's level courses in homeland security and criminology programs, as well as those who work in homeland security and national security affairs.