Terrorism from below has been an evolutionary rather than a revolutionary part of American history. Contemporary terrorists have a great deal in common with their historical counterparts. A review of the ideologies, goals, and actions of early American extremists and terrorists demonstrates that they are not a new breed of political activist, but are the historical outgrowth of the vigilante tradition that has been an integral part of American society from colonial times to the present. During the 16th and 17th centuries, European colonists who immigrated to North America often resorted to political mob violence as a reasonable method for expressing their political, social, and economic grievances. As the American frontier moved westward, many frontier families who were faced with life-threatening situations became rural radicals who developed extremist views that became the focus of their lives: strong, self-reliant communities were needed to conquer the physical hardships of colonial life; Christianity was the one true faith; government rule should act to defend all white people, not just the select few in power; and if the people legally expressed their grievances to those in power, and such grievances failed to bring about change, then mob action was justified in order to restore liberty. Some colonists, and later on, Americans went from extremism to political violence. Terrorist activities during the first 350 years of American history can be divided into three categories: scapegoating vigilantism, patriot militias, and left-wing terrorists. Today’s extremist and terrorist groups are not radical, but seek to return to an era of simplicity. Law enforcers have a mixed legacy of involvement with early terrorism. Historically, law enforcers supported the goals and activities of vigilante terrorists, but have been expected to suppress other groups—patriot militias and left-wing radicals. Today’s terrorists view law enforcement as the historical enemy and mourn the end of law enforcement’s support of vigilantism.