This book constitutes the refereed proceedings of the IEEE International Conference on Intelligence and Security Informatics, ISI 2006. Gathers 39 revised full papers, 30 revised short papers, and 56 extended poster abstracts, organized in topical sections including intelligence analysis and knowledge discovery; access control, privacy, and cyber trust; surveillance and emergency response; infrastructure protection and cyber security; terrorism informatics and countermeasures; surveillance, bioterrorism, and emergency response.