This book is an investigation into the contribution made to the Celtic Revival in Ireland in nineteenth and early twentieth centuries by the Roman Catholic Church. It aims to identify the major clerical figures involved; to examine what they contributed to revivalism; and to examine their reasons for the propagation of the Gaelic language and its culture. It will be suggested that Celtic revivalism, so-called, was not an entirely new ideology, but rather a re-emergence of an older ethnic nationalism, based on language and faith, already discernable, significantly enough, in the writings of seventeenth century clerical figures. It is argued that the legacy of these clerics permeated the worldview of nineteenth century clergymen, who, in consequence, kept alive this older ethnic nationalism. The attitude of the nineteenth century Roman Catholic Church to Gaelic Culture is examined. The Clerics played the leading role in founding language organizations: The Gaelic Society; The Society for the Preservation of the Irish Language (SPIL), The Gaelic Union and The Gaelic League. They were also prominent in the success of the Gaelic Athletic Association (GAA). The Clerics shaped the ideology of the revivalist movement through the creation of two new literatures: one in the Irish language but also one in English which, for practical purposes, was the language through which they could most easily reach the populace with their revivalist message.