Maximilian I's prayer book, printed in Augsburg in 1513, contains drawings by the most famous German Renaissance artists: Albrecht Dürer, Hans Burgkmair, Lukas Cranach, Hans Baldung called Grien, Albrecht Altdorfer and Jörg Breu were commissioned by the emperor to decorate a printed liturgical text with filigree marginal illustrations. Only one of ten surviving copies contains these pen and ink drawings, whose function - whether preparatory drawings for woodcuts or autonomous drawings - has long divided art history. A second edition with woodcuts by Hans Schäufelin was produced at the same time. This study records the surviving inventory of the prayer books and traces the history of their creation.