Monitoring terrorists' use of the Internet provides an opportunity to collect information about the root causes driving terrorist warfare. Terrorist groups and their supporters are extensively active on Internet websites and in chat rooms and forums. Tracking such sites yields information about their grievances, ideologies, ambitions, and other factors that motivate them to conduct terrorist activities. The methodology presented in this chapter aims to enable counterterrorism analysts to hierarchically decompose the underlying factors driving a terrorist insurgency, by focusing on the content of terrorist-related websites.