Ollam (ollav), named for the ancient title of Ireland's chief poets, celebrates the career of Tomas O Cathasaigh, Henry L. Shattuck Professor of Irish Studies at Harvard University, who is one of the foremost interpreters of the rich and fascinating world of early Irish saga literature. It is a complement to his own book of essays, Coire Sois, the Cauldron of Knowledge: A Companion to Early Irish Saga, also edited by Matthieu Boyd (University of Notre Dame Press, 2014), and a sequel to his classic monograph The Heroic Biography of Cormac mac Airt (Dublin Institute for Advanced Studies, 1977) and as such it begins to show the richness of his legacy. The essays in Ollam represent cutting-edge research in Celtic philology and historical and literary studies. They form three clusters: heroic legend; law and language; and poetry and poetics. The 21 contributors are among the best Celtic Studies scholars of their respective generations, whether they are rising stars or great professors at the finest universities around the world. The book has a Foreword by William Gillies, Emeritus Professor at the University of Edinburgh and former President of the International Congress of Celtic Studies, who also contributed an essay on courtly love-poetry in the Book of the Dean of Lismore. Other highlight include a new edition and translation of the famous poem Messe ocus Pangur ban; a suite of articarticles on the ideal king of Irish tradition, Cormac mac Airt; and studies on well-known heroes like Cu Chulainn and Finn mac Cumaill. This book will be a must-have, and a treat, for Celtic specialists. To nonspecialists it offers a glimpse at the vast creative energy of Gaelic literature through the ages and of Celtic Studies in the twenty-first century.