As relations deteriorated between the United States and the Soviet Union after World War II, the Truman administration faced increased pressure to preserve United States national security. One of its most important responses to this expanding Cold War was the National Security Act. Passed by Congress in July 1947, this legislation established a new, potentially revolutionary, presidential advisory body--the National Security Council. The primary role of the National Security Council was advising the president concerning matters involving United States national security. It was not until the outbreak of the Korean War and the development of NSC 68 that Truman began to place more than minimal emphasis on the new organization’s recommendations. The implementation of NSC 68 in 1950 revolutionized how United States national security policy was to be conducted. However, besides its role in the development of this one national security paper, the National Security Council wallowed in relative obscurity throughout the Truman administration. It was not until the inauguration of the Eisenhower presidency that the National Security Council began to fulfill the role envisioned by the 1947 National Security Act. This thesis examines the role played by the National Security Council in the development and implementation of United States national security policy during the Truman and Eisenhower administrations. It focuses specifically on the importance of the National Security Council’s basic national security papers in determining policy. It concludes that from a relatively unimportant position in the Truman administration, the National Security Council developed under Eisenhower into an instrumental advisory body where national security problems were discussed, debated, and acted upon. / Master of Arts