In 2002 Afghanistan began to experience a violent insurgency as the Taliban and other groups conducted a sustained effort to overthrow the Afghan government. Why did an insurgency begin in Afghanistan? Answers to this question have important theoretical and policy implications. Conventional arguments, which focus on the role of grievance or greed, cannot explain the Afghan insurgency. Rather, a critical precondition was structural: the collapse of governance after the overthrow of the Taliban regime. The Afghan government was unable to provide basic services to the population; its security forces were too weak to establish law and order; and there were too few international forces to fill the gap. In addition, the primary motivation of insurgent leaders was ideological. Leaders of the Taliban, al-Qaida, and other insurgent groups wanted to overthrow the Afghan government and replace it with one grounded in an extremist interpretation of Sunni Islam.