This book constitutes the refereed proceedings of the IEEE International Conference on Intelligence and Security Informatics, ISI 2005, held in Atlanta, GA, USA in May 2005. The 28 revised full papers, 34 revised short papers, and 32 poster abstracts presented were carefully reviewed and selected for inclusion in the book. The papers are organized in topical sections on data and text mining, infrastructure protection and emergency response, information management and security education, deception detection and authorship analysis, monitoring and surveillance, and terrorism informatics.