There was no native tradition of theatre in Irish. Thus, language revivalists were forced to develop the genre ex nihilo if there was to be a Gaelic drama that was not entirely made up of translations. The earliest efforts to do so at the beginning of the 20th century were predictably clumsy at best, and truly dreadful at worst. Yet by the 1950s, a handful of Gaelic playwrights were producing plays in Irish worthy of comparison not only with those by their Irish contemporaries working in English but also with drama being produced elsewhere in Europe as well as in North America. Obviously, Gaelic drama transitioned with surprising speed from what one early critic called ‘the Ralph Royster Doyster Stage’ to this new level of sophistication. This book argues that this transition was facilitated by the achievements of a handful of playwrights – Piaras Beaslai, Gearoid O Lochlainn, Leon O Broin, Seamus de Bhilmot, and Walter Macken – who between 1910 and 1950 wrote worthwhile new plays that dealt with subjects and themes of contemporary interest to Irish-speaking audiences, in the process challenging their fellow dramatists, introducing Gaelic actors to new developments and styles in world theatre, and educating Gaelic audiences to demand more from theatre in Irish than a night out or a chance to demonstrate their loyalty to the revivalist cause. This book, which discusses in some detail all of the extant plays by these five transitional playwrights, fills a gap in our knowledge of theatre in Irish (and indeed of theatre in Ireland in general), in the process providing clearer context for the appreciation of the work of their successors, playwrights who continue to produce first-rate work in Irish right to the present day.