Medieval learning always relied on written texts. Nevertheless, medieval schools and the universities themselves in the first decades of their existence were usually deprived of libraries. However, university libraries (of faculties, of colleges, of professors) progressively appeared in the fourteenth and fifteenth centuries, although generally at a limited scale. University libraries reflected up to a certain point the structures and contents of the lectures given in the classrooms. But, as far as they gave masters and students (or at least a part of them) access to a large amount of texts and knowledges otherwise inaccessible through the only means of memory or isolated books, they might also have contributed to the development and orientation of the contents of teaching and teaching methods. Eventually, from a wider point of view, the existence of university libraries probably changed the very relationship to written culture, the image of knowledge, the practical forms of intellectual work for university men and the institutional and financial frame of medieval universities, and paved the way for the emergence of the printing press.