The main feature of the International System in the Post- Second World War and in the Post-Cold War, which, I believe, influenced the perception of both Dutra s and Collor s administrations about the way that the Brazilian foreign policy should have been conducted, was the incontestably appearance of the United States as a worldwide leader in a new international order. Therefore, the political diagnostic of the importance to centralize relations with that country conditioned the foreign behavior of the Brazilian government in those moments of the Brazilian diplomatic history. Nevertheless, although both presidents have adopted a similar directive on the conduction of the Brazilian foreign affairs, it is in the dimension of internal process of decision-making that striking differences have appeared. In my opinion, the organizational and symbolic features of the diplomatic agency conditioned the way the perception of the alliance with United States was conducted by the Executive in both periods. In that direction, the present dissertation supports the hypothesis that those differences in the external behavior of Brazil are related, fundamentally, to the relation of autonomy and control between the Presidency of Republic and the Itamaraty for the decision-making process.