The western Roman empire left a double cultural legacy: Christianity, of a kind which acknowledged the authority of the bishop of Rome, and Latin, the language of Roman Christianity. This chapter tells the story of lexicography in the lands where Roman Christianity was practised and the Latin language was read. These lands correspond roughly with modern western and central Europe, but the concept ‘Europe’ was not in general use until the very end of this period, and need not distract us here. The Islamic and Orthodox neighbours of Latin Christendom had their own lexicographical traditions, which are treated in Chapters 8, 11, and 12. Within Latin Christendom, Jews contributed to the lexicography of at least three vernacular languages (French, Italian, and Czech), and these contributions are documented here, but the learned Jewish tradition of Hebrew lexicography is treated separately in Chapter 9. The pagans on the edges of Christendom were illiterate, and became literate only as they became Christian.