The study looks at eight cases of dissemination of encyclopedic knowledge in the European Middle Ages. As a major source of insight, the author draws on the prologues of the selected Latin (e.g. "Elucidarum", "Hortus delicarium"), German (Lucidarius, Hiltgart von Hürnheim's "Encyclopedia"), French ("Livre de Sidrac", Brunetto Latini, Christine de Pizan), and Spanish works, examining them from the perspective of communication science. The results point up not only a number of constants but also some surprises in connection with the vehicles, forms, and audiences of encyclopedic knowledge dissemination.