This chapter presents the phenomenon to be studied, revolutionary terrorism. The chapter has three parts. In the first, the ideology of this form of terrorism and its historical precedents are discussed. The basic tenet of the revolutionary terrorists was that violence was necessary to provoke insurrection among the broad working class and its allies against capitalism and liberal, bourgeois democracy. The different mechanisms through which terrorist violence may be linked to mobilization are analyzed, paying special attention to the anarchist doctrine of “propaganda by the deed” developed at the end of nineteenth century. The second part explores revolutionary terrorism as a late and deviant branch of the revolutionary activity that starts with the success of Fidel Castro and Ernesto “Che” Guevara in the Cuban revolution. In more advanced Latin American countries, Uruguay and Argentina, rural guerrilla groups of the Cuban type evolved into urban, underground groups; and this is the form of violence that traveled to affluent countries in the early 1970s. The third part of the chapter provides detailed data about the characteristics of terrorist revolutionary violence (levels of lethality, evolution, target selection, selectivity of violence, and mode of organization) based on an original data set.