This chapter examines the history of counter-terrorism and the terrorism and terrorist threats to which it responds in the United States pre-9/11. It provides an overview of the different types of domestic and international terrorism and movements that have affected or targeted America historically and been the focus of counter-terrorism. Since the attacks of 9/11, political, public, media and academic focus on terrorism and counter-terrorism has proliferated. The chapter also examines the history of counter-terrorism in the United States, looking at different developments, policies and approaches. It presents the ways in which counter-terrorism has changed in response to both threats and attacks, political and ideological agendas and interests, and pressure and criticism, as well as challenges, mistakes and failures. Terrorism and terrorist groups that are covered by American counter-terrorism can be divided into two types based on the perpetrator and target: domestic and international.