Process helps determine substance. Understanding the dynamics of foreign policymaking would enable us to make predictions as to what is most likely to be decided in a particular set of circumstances. Foreign policy is not of government, it is of the state; and therefore, involves other institutions and agencies than the executive branch, or broadly speaking, the government. That makes it an intricate task to analyze the foreign policymaking process of any country in general and that of the US in particular because of the complexity of its governmental machinery, owing to the concept of limited government through separation of powers and checks and balances. Complexity of the governmental machinery not only makes it difficult to locate the origin of a policy directive but also makes its passage lengthy and complicated. No matter how a particular policy gets originated, in order to get implemented, it has to make its way through various institutions and agencies of foreign policymaking, each of which has its own motives, mindset, and most importantly, degree of authority. In order to make this process comprehendible, this paper evaluates the role of different institutions in foreign policymaking, explains different models of foreign policymaking, and summarizes the evolution of the patterns of foreign policymaking in the US