This Chapter introduces some of the key questions that are addressed by the authors within this book. What do we mean by a “new anti-terrorism era” and what, if anything, is new about the security challenges that we face today? What contribution can science and technology make to counter terrorism? What are the public policy responses and how should they be judged? What is the extent of international cooperation in anti-terrorism science and technology development? What are the implications of the new security environment for the governance of science and technology? The answers to these questions are critical to formulating sound science and technology policies to confront one of the key international security challenges of our era.