Terrorists are continuously learning to utilize the Internet as an accessible and cost-effective information infrastructure. Since a constant manual monitoring of terrorist-generated multilingual web content is not a feasible task, automated Web Intelligence and Web Mining methods are indispensable for efficiently securing the Web against its misuse by terrorists and other dangerous criminals. Web Intelligence and Security contains chapters by the key speakers of the NATO Advanced Research Workshop on Web Intelligence and Security that took place on November 18-20, 2009 in Ein-Bokek, Israel. T