Barry Eidlin’s book, Labor and the Class Idea in the United States and Canada (Cambridge University Press, 2018) explains why unions are weaker in the United States than they are in Canada, but have not always been that way. Indeed, unionization rates were virtually identical for much of the twentieth century, then diverged in the 1960s. Against dominant accounts focused on long-standing differences in political cultures and institutions, Eidlin argues that the divergence resulted from different ruling party responses to working class upsurge in both countries during the Great Depression and World War II. In Canada, an initially more hostile state response ended up embedding “the class idea”—the idea of class as a salient, legitimate political category—more deeply in policies, policies, and practices than in the United States, where class interests were reduced to “special interests.” In this symposium, three noted labor scholars engage critically with the book. Cedric de Leon interrogates Eidlin’s account of the role of racial divisions in explaining divergence, noting “more persistence and convergence than there is rupture and divergence” between these two countries on this issue. Nelson Lichtenstein’s critique focuses on the exceptionally vociferous character of US employer hostility, which he argues that Eidlin downplays. And Judith Stepan-Norris notes the surprising lack of actual class actors in a book about class organization, while raising interpretive questions about the relation between labor and the Communist Party in both countries. Eidlin concludes the symposium with a response to the critics.