The origins of the Cold War continue to provoke debate among historians. Published on the fiftieth anniversary of the start of the Cold War, this issue of Socialist History contributes to the debate by reviewing some of the key themes of the period from a variety of angles. Fred Halliday examines US foreign policy in the light of the Truman Doctrines and the Marshall Plan. John Saville looks at the contrasting fates of Greece, Italy and Spain in the postwar years and what moves the West took to keep them out of the Soviet economic weakness to its ultimate defeat. Heather Williams discusses what Tito’s defiance of Stalin reveals about the nature of the early Cold War; and Don Watson considers the case of Konni Zilliacus MP, denounced by the British Government in the 1940s for his close association with communism.