This book 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 challenge of creating a literature in English that would be independent of the English literary tradition. The use of Hiberno-English is both a literary device and a practice that bears on the question of an Irish national identity. This work examines above all the uses of Hiberno-English as a literary device. One of the potential functions of a literary text is to call into question received ideas, and the texts discussed here do this with the help of Hiberno-English. Here, this dialect stands as a form of authenticity which is questioned and through which received ideas are criticised. This book also contains a large corpus whose primary purpose is to record the abundance of Hiberno-English in the works under review. The corpus provides a gloss and outlines the grammatical and phonetic features of Hiberno-English.