One of the factors that contributed to the success of the Marshall Plan was that economic recovery was already occurring in Europe, and the massive influx of funds sped it up considerably. Another factor was the fact that, unlike US efforts after World War I, there were far fewer conditions placed on the funds that were disbursed. Another is, quite simply, scale. The Marshall Plan represented a very significant portion of US GDP. Finally, and this relates more to domestic politics, the Marshall Plan was successful because it followed on the heels of the New Deal, which had prepared Americans, if you will, for these types of massive recovery efforts. It also occurred during a uniquely internationalist moment in US foreign policy, when Americans approvingly looked at their nation as a world leader. Whether it would work equally well in other places is open for debate, but it is worth noting that the US invested billions in rebuilding Japan and South Korea, and in fact the Marshall Plan accounted for less than half of the aid, including military aid, sent to countries around the world in the wake of World War II. An important book that emphasizes Britain's role in the Marshall Plan is Michael Hogan's The Marshall Plan: America, Britain, and the Reconstruction, of Western Europe. Christine Borgwardt's A New Deal for the World also emphasizes the internationalist context for the Marshall Plan, especially the desire to create economic security, though it doesn't study the Marshall Plan as such.