The chapter argues that, with the publication of Los siete locos (The Seven Madmen) in 1929, Roberto Arlt produced the first major Argentine novel whose ideological topics, ways of representation, systems of characters, and spatial inventions, far from finding their place among the national literary traditions, establish a dialogue with the great novels of metropolitan modernity of the time: James Joyce’s Ulysses (1922), John Dos Passos’ Manhattan Transfer (1925), and Alfred Döblin’s Berlin Alexanderplatz (1928). The modern city, the cosmopolitan city of urban mixture and modernization, is the grand stage for the aesthetic, ideological, cultural, and social conflict in Arlt’s literature. In this sense, as a writer, journalist, and playwright, Arlt is the one who best expresses the disruption of an order and the instability implied by the impact of modernization on Argentine culture in the early twentieth century.