This thesis studies the uses of the dialect known as Hiberno-English in the works of several canonical Irish writers of the twentieth century: James Joyce, Flann O'Brien, George Bernard Shaw and Brian Friel. Irish writers of this period faced the problem of creating a literature in English that would be independent of the English literary tradition. The use of Hiberno-English is therefore both a literary device and a practice that bears on the question of an Irish national identity.