The unwillingness of the Soviet Union to allow the creation of independent and democratic states in Eastern Europe, and the failure of East and West to reach a compromise on Germany, left many Americans puzzled. Why were the Soviets acting as they did? Moreover, how should the United States respond? This lesson will consider containment through the use of original documents, mostly from the Truman Presidential Library. They will study what it meant in theory, and then examine the first two major instances of its application—the Truman Doctrine and the Marshall Plan.