A revolutionary change in the shape of inter-American relations has taken place in the last few years. The most casual observer is aware of this fact but it is difficult to assess the effects of the changes and to determine the prevailing tendency for the future. Fidel Castro's takeover of Cuba in 1959 appeared for a while to be just another Latin American “revolution” but it soon developed into a major threat to United States hegemony, confirmed by the ensuing missile crisis which marked the entry of another great power into the Western Hemisphere, a major zone of United States influence. Nothing in the Americas has been the same since then, although the effects of Castro's regime on other American States continue to be debated with more heat than light. Results tend to reflect previously established positions on the nature both of Castro's government and that of the states influenced by his activities.