This short book is intended to serve as a practical guide to Gaelic language sources (as opposed to administrative or ecclesiastical records in Latin, French or English) for the history of these communities in the high Middle Ages, laying emphasis on published texts for which English translations are available. Under six headings (annals, genealogies, poems, prose tracts and sagas, legal material, colophons and marginalia), it discusses not only the nature of the sources themselves, the purposes for which they were originally created, and their survival and availability to researchers, but also how to glean usable historical information from them.