Extending and challenging Pascale Casanova’s account of world literary systems in The World Republic of Letters, this chapter argues that after World War I American and Irish writers boldly remade the world literary system long dominated by Paris and London. In the context of European imperial decline and emerging American ascendancy, American and Irish émigré writers produced dazzling new works that challenged the authority of London and Paris to establish literary value. After World II, Paris remained a strong but considerably weaker cultural capital, and New York assumed London’s former position as the major capital of the Anglophone literary world. During the Cold War, an assertive American literary establishment repurposed the literature that had once challenged English and French literary authority to boost the global cultural prestige of the United States and contest Soviet conceptions of “world literature.”