This is the first comprehensive study--completely in Gaelic--of the work of the great nineteenth century collector, translator, editor, and publisher of Gaelic verse, an important figure in the Gaelic revival, and, indeed in the development of Anglo-Irish literature. It has a detailed analysis of his sources, editions, and connections in the literary world. Sean O Dalaigh (John O'Daly) was born in Waterford (1800-1878). He was a pioneer in promoting the use and advancement of the Irish language in his own time. He authored a prominent grammar of the vernacular (Self-Instruction in Irish) and published similar works by others all of which helped revolutionize the production of handbooks in the area. Another main accomplishment was bringing Gaelic literature to notice. His "Reliques of Irish Jacobite Poetry" gave access to the to the texts of eighteenth-century Irish political verse and the world view reflected in it. O Dalaigh's "Poets and Poetry of Munster" opened up views on post-Classical Irish composition. He founded the Celtic Society, a learned society dedicated to the production of texts in Gaelic, in Dublin during the mid-1840s and the Ossianic Society in 1853. The aim of the Ossianic Society was to collect and publish the poems and tales of Oisin and the Fianna, especially those preserved in extant manuscripts in the Irish language. O Dalaigh's career intersects with a number of critical issues relating to Irish identity immediately prior to his era, during his own lifetime, and afterwards. This book restores to view people, publications, and problems thet were well known in their own age but have now been unjustifiabily overlooked. "Sean O Dalaigh" should become standard reading for all those interested in nineteenth-century Ireland, in the history of Irish civilisation, manuscript materials, publishing, and scholarship.