The history of the two halves of post-war Europe cannot be told in isolation from one another. The legacy of the Second World War--and the pre-war decades and the war before that--forced upon the governments and peoples of east and west Europe alike some hard choices about how best to order their affairs so as to avoid any return to the past. One option--to pursue the radical agenda of the popular front movements of the 1930s--was initially very popular in both parts of Europe (a reminder that 1945 was never quite the fresh start that it sometimes appears). In eastern Europe some sort of radical transformation was unavoidable. There could be no possibility of returning to the discredited past. What, then, would replace it? Communism may have been the wrong solution, but the dilemma to which it was responding was real enough. In the West the prospect of radical change was smoothed away, not least thanks to American aid (and pressure). The appeal of the popular-front agenda--and of Communism--faded: both were prescriptions for hard times and in the West, at least after 1952, the times were no longer so hard. And so, in the decades that followed, the uncertainties of the immediate post-war years were forgotten. But the possibility that things might take a different turn--indeed, the likelihood that they would take a different turn--had seemed very real in 1945; it was to head off a return of the old demons (unemployment, Fascism, German militarism, war, revolution) that western Europe took the new path with which we are now familiar. Post-national, welfare-state, cooperative, pacific Europe was not born of the optimistic, ambitious, forward-looking project imagined in fond retrospect by today's Euro-idealists. It was the insecure child of anxiety. Shadowed by history, its leaders implemented social reforms and built new institutions as a prophylactic, to keep the past at bay.