Definitions of terrorism are proposed, and a model is presented for distinguishing legitimate from illegitimate terrorist actions by States and groups. The importance of media coverage to terrorists is discussed, and guidelines for media coverage are presented. Counterterrorist policies and tactics in the United States, Great Britain, Israel, and Italy are described. Investigation of domestic terrorism, including intelligence gathering and undercover operations, is discussed with a focus on the police response. A police perspective on researching terrorism also is offered. Antiterrorism legislation in the United States is reviewed, and the efforts of the Office for Counterterrorism and Emergency Planning are described. Finally, the need for international cooperation in combating terrorism is discussed. Chapter tables and notes.