This chapter examines the role that the horizontal diffusion of a new regime model and vertical imposition by great power US played in the Latin American coup wave. Brazil's overthrow of democracy in 1964 served as a model for other Latin American militaries, which sought to emulate the new type of development-oriented, institutionalized authoritarianism. Moreover, superpower US supported the spread of reactionary autocracy, fearing the proliferation of Communism during the COld War. But contrary to many early observers, the US was far from being the prime mover in the coup wave, as the recent declassification of documents confirms. Instead, Latin American elites had ample reasons to combat the perceived threat of Communism on their own and would most likely have ousted left-populist governments even without US involvement. In opposing Cuba-inspired left-wingers in Latin America, US officials were swayed by the same cognitive shortcuts that instilled excessive fear in Latin America's conservative sectors.