Intelligence and Security Informatics (ISI) has become an important research field after the tragic event of September 11, 2001. Researchers in computer and information science have a unique opportunity (and obligation) to contribute to international security via advanced IT research. A series of conferences on ISI has been organized in US since 2003, in Pacific Asia since 2006, and in Europe since 2008. More details about this series of conferences can be found at http://www.isiconference.org/. These activities have brought together researchers, practitioners, and policy-makers to support counterterrorism and homeland security mission. This book, INTELLIGENCE and SECURITY INFORMATICS: TECHNIQUES & APPLICATIONS, presents a collection of works discussing terrorism informatics, information sharing, data mining, intelligence and crime analysis, infrastructure protection, privacy protection, information surveillance, and emergency response. The authors come from nine different countries and contribute a total of twenty-two chapters of advanced and high-impact ISI research. The audiences of this book include: (1) public and private sector practitioners in the national/international and homeland security area; (2) consultants and contractors engaging in on-going relationships with federal, state, local, and international agencies on projects related to national security; (3) graduate level students in computer science, information science, public policy, information security, criminology, and terrorism study; and (4) researchers engaging in security informatics, homeland security, information policy, knowledge management, public policy, and counterterrorism research.