The Old English words in the Corpus Glossary constitute one of the oldest extant texts in the English language, and one of the three longest in the Mercian dialect. Linguists now agree that the glossary was compiled somewhere in Mercian territory during the eighth century. Palaeographical evidence points to the eighth century as the period of compilation. Concerning two important questions, linguistic opinion seems at present vague and uncertain: First, to what extent is the language of Corpus the result of dialect mixture? Second, what is the relationship between the language of Corpus and that of the most important of the texts now looked upon as Mercian, the Vespasian Psalter?