The United States arid the several large Third World countries are now in the early stages of a major change in their relations. And compared to the traditional powers of Europe, or to Japan, the rising middle powers of the Third World have population and natural resource bases more nearly comparable to those of the United States and the Soviet Union. The rising political, economic, and military power and the large aggregate size of leading Third World states indicate they will eventually play a global role. This will require new modes of response by the United States as such issues as population growth, natural resource control, nuclear proliferation, and trade relations become increasingly important.