Taking medieval Paris as a case study, the author examines the evidence for the book trade in the Middle Ages, from commercial, cultural, and social perspectives. If book production was concentrated in the early Middle Ages in monasteries and on religous texts, after 1200 university texts and lay vernacular works began to comprise a greater proportion of the output, aimed at new markets. These new audiences supported a variety of craftsmen, variously regulated by the University and the secular authorities, concentrated around the cathedrals. Booksellers, libraires, increasingly supervised the diverse craftmen engaged in book production.