Epistolary Modernism reads British and Irish writing of the 1920s through the 1950s with a focus on the way authors use fictional letters and verse epistles to communicate a renewed sense of literature as public speech, even as they saw privacy curtailed and surveillance increased. Letters enable late modernist writers to call attention to the way literature straddles the gap between private experience and public declaration. Virginia Woolf, W.H. Auden, Louis MacNeice, Graham Greene and Elizabeth Bowen all use letters to reveal a late modernist belief in literature as an exchange between an author and a reader -- a bridge between times and perspectives -- even as they trouble the possibility of any clear communication or meaning. The implied exchange in letters requires a sense of correspondence: a letter demands both interpretation and a reply. But a letter is always already too late. Epistolary Modernism reads letters as a stand-in for the literary period of late modernism itself, an epoch of writing characterized by a sense of coming too late to history and to literary tradition. The project considers fiction and poetry published in the 1920s through the 1950s in relation to historical and cultural events of the period, arguing that the sense of belatedness and temporal disjuncture letters create fundamentally links the structure and materiality of the text to the social and political concerns of its author. These writers composed literature attuned to historical events and the simultaneously occurring ordinary moment, leading to an increasingly interconnected, and socially-responsible art borne from the historical impasse of the thirties, the Second World War and its political legacy. Letters enable these writers to continue aesthetic experiments while simultaneously addressing politics, society, and the purpose of literature itself.