This is the first comprehensive, scholarly history of Trinity College Library Dublin. It covers the whole 400 years of the Library's development, from its foundation by James Ussher in the seventeenth century to the electronic revolution of the twenty-first century. Particular attention is given to the buildings and to the politics involved in obtaining funding for them, as well as to the acquisition of the great treasures, such as the Book of Kells and the libraries of Ussher, Claudius Gilbert and Hendrik Fagel. An important aspect is the comprehensive coverage of legal deposit from the beginning of the nineteenth century, viewed for the first time from the Irish perspective. The book also draws parallels with the development of other libraries in Dublin and with those of the universities of Oxford and Cambridge, and features throughout the individuals who influenced the Library's development - librarians, politicians, readers, book collectors and book thieves.