The United States currently has interests in the South Atlantic and Antarctica which have traditionally taken a back seat to U.S. interests in other regions. In the closing years of the twentieth century, those interests likely will receive more attention as the United States and the global community shifts its attention from the traditional focus on East- West issues and their conflict potential to more nationalist interests. This thesis examines U.S. interests in the South Atlantic and Antarctica and evaluates the potential challenges to those interests. The thesis concludes that, while its interests in the South Atlantic remain, the United States will find it increasingly more difficult to extend its influence as the countries of the region exert more national will and as extra-hemispheric actors gain a more significant foothold.