This is the first volume in the series to deal with a national library. Llyfrgell Genedlaethol Cymru, the National Library of Wales, was founded with the expressed purpose of preserving the material of the literary culture and history of Wales. The number of medieval English language manuscripts, while substantial, does not form as great a proportion of the holdings as in other libraries in Britain, and a special feature of the collection is that the manuscript context for some English texts is one in which Welsh is the main language. The collection is thus relatively unexplored for its Middle English holdings, and of the manuscripts indexed here fewer than half are listed in the Index of Printed Middle English Prose; they contain awealth of materials, most notably in historical writings, scientific texts, and prophecies. The introduction sets the wider context for the manuscripts by discussing the history of the Library and the way in which its major collections were brought together.