2010 saw the publication of the Proceedings of the 1st International Conference on the Science of Computus in Ireland and Europe, which took place in Galway, 14–16 July, 2006. That first collection, which had the sub-title Computus and its Cultural Context in the Latin West, AD 300–1200, brought together papers by ten of the leading scholars in the field, on subjects ranging from the origins of the Annus Domini to the study of computus in Ireland c. 1100. All those who participated in the Conference were unanimous that a second, follow-up event should be organized, and that duly took place (also in Galway), 18–20 July, 2008. The proceedings of that Conference are published in this current volume. The topics covered in the 2nd Galway Conference ranged from the general – but vitally important – vocabulary of computus (i.e., the technical terminology developed by computists to describe what they were doing) to the origins of the different systems used to calculate the date of Easter in Antiquity and the Early Middle Ages. In addition, there was discussion also of the great debates about Easter, epitomized by the famous Synod of Whitby in AD 664, and the role of well-known individuals in the evolution of computistical knowledge (e.g., Anatolius of Laodicea, the African Augustalis, Sulpicius Severus, Victorius of Aquitaine, Cassiodorus, Dionysius Exiguus, Willibrord, the ninth-century Irish scholar-exile, Dicuil, as well as the late-tenth century Abbo of Fleury). Immo Warntjes is lecturer in Medieval History at the University of Greifswald (Germany). Besides computistics, his main areas of research include the use of languages in Early Medieval Europe, succession to high offices, high and late medieval burial practices, and German, English, and Irish political history and culture. Dáibhí Ó Cróinín lectures in history at NUI, Galway, where he is the Director of The Foundations of Irish Culture project. His research interests are Ireland, Britain and Europe during the Early Middle Ages, computistics, Medieval Latin Palaeography and Irish traditional music and song.