Long obscured by the more dramatic activities of post–World War II student activists, the history of the Japanese left-wing student movement during its formative period from 1918 until its suppression in the 1930s is analyzed here in detail for the first time. Focusing on the Shinjinkai (New Man Society) of Tokyo Imperial University, the leading prewar student group, Henry DeWitt Smith describes the origins and evolution of student radicalism in the period between the two World Wars. He concludes with an analysis of the careers of the Shinjinkai members after graduation and with an explanation of the importance of the prewar tradition to the postwar student movement.