In over 2,000 entries, the Companion to Irish Literature surveys the Irish literary landscape across some sixteen centuries, describing its features and landmarks. Entries range from ogam writing, developed in the 4th century, to the fiction, poetry, and drama of the 1990s; and from Cu Chulainn to James Joyce.

There are accounts of authors as early as Adamnan, 7th century Abbot of Iona, up to contemporary writers such as Roddy Doyle, Brian Friel, Seamus Heaney, and Edna O'Brien; and individual entries on all major works, from Tain Bo Cuailngethe Ulster saga reflecting the Celtic Iron Age - to Swift's Gulliver's Travels, Edgeworth's Castle Rackrent, O Cadhain's Cre na Cille, and Banville's The Book of Evidence.

It offers a wealth of information on general topics, ranging from the stage Irishman to Catholicism, Protestantism, the Irish language, and university education in Ireland; and on genres such as annals, bardic poetry, and folksong. The majority of entries include a succinct bibliography, and the volume also provides a chronology and maps.

Throughout the Companion, cross-references give access to a network of interrelated topics, texts, and individuals, making it an ideal browsing book as well as a mine of information.