Book excerpt: As terrorist organizations such as Al-Qaeda have been transformed from hierarchical organizations to more fluid networks, countering terrorism requires an understanding of networks. These networks evolve rapidly in response to actions to thwart them, leading to an ongoing struggle of terrorist and antiterrorist networks. In this chapter, Boaz Ganor examines the evolving threat of terrorist networks and network-based responses. As he notes, “it takes a network to beat a network.” He also examines direct and indirect implications for business organizations.