By October of 1973 the United States was facing the possibility of an energy crisis—a shortage of domestic petroleum supplies. The Arab oil embargo and international petroleum price increases exacerbated this crisis and acted as a constraint upon United States foreign policy during this period. Three constraints are relevant to the energy crisis; economic, alliance, and perceptual,. A review of the literature on foreign policy constraints gives an explanation of the nature of these constraints and past United States foreign policy. In general economic constraints have been important in United States foreign policy formulation, because both the public and policy-makers attach high value to the attainment of economic goals. AlliAnce constraints have been of varying degrees of importance and the significance of an alliance constraint upon United States foreign policy is usually determined by such factors as the, structure of the international system, the degree of integration, the nature of warfare, the importance of interests involved, the strength of the major powers, and the expectations of allies. Perceptions inevitably influence foreign policy because a policy-maker never has an accurate image of the international situation. In addition, there has been a tendency in American foreign policy formulation to create crises where none really exists. The United States experience with foreign policy constraints during the energy crisis seems to be consistent with this historical experience. Although domestic policy probably could have minimized the harmful effects of energy shortages, the concept of political economy surrounding the problem placed pressure upon policy-makers to find international solutions. Alliance constraints forced the United States to operate through collective action. Crisis perceptions also heightened the urgency of finding solutions. The United States policy which emerged from this period stressed mediation in Mideast negotiation and international cooperation to solve energy shortages. These policies were the direct result of constraints imposed by the energy crisis.