When at Christmas 1933 the Belgian Workers' Party adopted the Plan de Man to guide its forward march to socialism, European critics of unfettered capitalist development listened carefully. Deeply worried by Hitler's legal rise to power, socialist activists and intellectuals were then searching for new answers to the crises of their day, and many believed that they had found a blueprint in the Plan. Inspired by the activist politician Hendrik de Man, a series of international plan conferences, assembling the entire spectrum of western European pro-socialist, non-Stalinist economists, met between September 1934 and October 1937. The changing nature of these debates exemplify the fate of European socialism in the mid-1930s, descending from optimistic belief in a democratic socialist future towards technocratic pragmatism in the space of thirty-seven months.