This introduction presents an overview of key concepts discussed in subsequent chapters of this book. The book is about doing critical terrorism studies, about researchers putting methodologies and methods to work, applying them to some set of texts, some field site or field of inquiry. Much of the knowledge about terrorism has been generated by a comparatively small group of scholars mostly in Western Europe and the United States. At the same time, even as the field of terrorism studies as a whole has remained less than innovative when it comes to theoretical development, the author argue that a theoretically, methodologically, and empirically diverse array of dissident literature began to emerge in 1980s. His point is to highlight the burgeoning dissident literature taking shape in 1980s, especially work focused on state-based terror targeting domestic and international populations. The book attempts to provide a review of critical methodologies and outline critical tools that exist in the study of terrorism.