Marxism in a Lost Century retells the history of the radical left during the twentieth century through the words and deeds of Paul Mattick. An adolescent during the German revolutions that followed World War I, he was also a recent émigré to the United States during the 1930s Great Depression, when the unemployed groups in which he participated were among the most dynamic manifestations of social unrest. Three biographical themes receive special attention: the self-taught nature of left-wing activity, Mattick’s experiences with publishing, and the nexus of men, politics, and friendship. Mattick found a wide audience during the 1960s because of his emphasis on the economy’s dysfunctional aspects and his advocacy of workplace councils—a popularity mirrored in the cyclical nature of the global economy.