This book constitutes the refereed proceedings of the International Workshop on Intelligence and Security Informatics, WISI 2006, held in Singapore in conjunction with the 10th Pacific-Asia Conference on Knowledge Discovery and Data Mining (PAKDD 2006).

The 32 revised full papers presented together with the abstract of the keynote talk were carefully reviewed and selected from numerous submissions. The papers are organized in topical sections on Web and text mining for terrorism informatics, cybercrime analysis, network security, and crime data mining.