The collapse of the Weimar Republic in 1933 was a disaster of world-historical dimensions. While most historians focus on the Social Democratic role in that debacle primarily within its German and European contexts, this essay examines it within the broader framework of the global history of democratic socialism in the twentieth century. By comparing Social Democracy's defeat in 1933 with the experiences of the Popular Unity Party in Chile in 1973, the Sandinistas in Nicaragua in 1989, and the African National Congress in South Africa in 1994, the essay examines the Socialist failure in 1933 from a new perspective and raises questions about the dilemmas faced by democratic socialist movements in bringing about radical change.