In American history there have arguably been three types of terrorism – two domestic and one transnational. The predominant expressions of domestic terrorism in the United States are rooted in ethnic and racial conflicts. Among the most important are aimed at the maintenance of racial hierarchies and specifically white supremacy. A second domestic form is rooted in the class conflicts of a rapidly expanding industrial society at the end of the nineteenth century and the beginning of the twentieth. This ‘revolutionary terrorism’ is rooted in the anarchist tradition, which garnered substantial amounts of attention but had shallow roots in the labour movement. ‘Transnational terrorism’ is likewise important in the American context. While carried out on American soil or against American outposts abroad, it’s often planned outside of it, or inspired by outside sources, and results from opposition to the United States’ global role. Richard Hofstadter observed that while political violence had been ubiquitous in American history, much of it had been carried out by groups of citizens against other groups, and that it has rarely shaken the political order. He likewise suggested that the most successful forms have been socially and politically conservative. This argument is explored in the three sections of my essay. The first two focus exclusively on domestic terrorism – racial/ethnic and revolutionary terrorism respectively. The third is more varied. Its emphasis is the transnational terrorism exemplified by September 11th, but it also explores domestic forms, notably the 1995 Oklahoma City bombing and recent terrorist attacks associated with the radical right.