The 'Leiden Glossary' provides a record of the understanding and interpretation of the patristic and grammatical texts studied at the Canterbury School of Theodore and Hadrian, regarded by Bede as the high point of Christian culture in early medieval England. Each entry in the 'Leiden Glossary' is provided with detailed commentary on the sources consulted by the two Canterbury masters (earlier glossaries; Isidore; Eucherius) and the later uses of the glossary by compilers of the Epinal-Erfurt and Corpus glossaries. The 'Leiden Glossary' is thus a key witness to one of the greatest schools of learning in the early Middle Ages.