This chapter explores the early twentieth-century phenomenon known as the roman-fleuve (river-novel) and proposes a model for understanding its place within French literary history. The origins of the term can be traced back to Romain Rolland’s Jean-Christophe, a multi-volume novel recounting the fictional life story of its eponymous protagonist. Although there are notable stylistic and thematic differences between it and the novel cycles of the other three proponents of the roman-fleuve form—Roger Martin du Gard, Jules Romains, and Georges Duhamel—Jean-Christophe provides the yardstick against which these later literary creations must be measured. Utilizing Rolland’s protagonist as its central reference point, the chapter contends that the roman-fleuve’s overarching ambition is to rework the notion of the modern subject in function of an alternative understanding of the individual and the collective. In a tumultuous era marked by war and the crumbling of religious and metaphysical certainties, this reconception of subjectivity inaugurated an innovative literary exploration of Bergsonian intuition and the Nietzschean overturning of ready-made systems of thought. Lying between the sentimentality of the romantics and the materialism of the positivists, the roman-fleuve was a landmark, if short-lived, example of French literary creativity blossoming in the arid ground of modernity.