Vernacular prayer books were by far the most commonly read book in the late medieval Low Countries. The mainstay of this vast corpus is the Book of Hours in the translation by Geert Grote (c. 850 manuscripts and 30 printed editions), founder one of the period’s most powerful religious reform movements. Nowhere else outside the Netherlands do so many manuscript and printed editions of this type of prayer book survive in the vernacular. While these books are fundamental for our understanding of religiosity, and of textual and visual literacy between 1380 and 1550 - a period that saw dramatic changes in the religious landscape and in book production - the sheer volume of material and its diversity has prevented researchers from fully grasping the nature and impact of this vibrant phenomenon.Pages of Prayer sets out to conduct the first large-scale investigation of this unique corpus by introducing a new approach - network philology - that studies all aspects of vernacular prayer books in their mutual interdependence. The project aims to chart the entire ecosystem of Dutch-language prayer books - including manuscripts, printed books, texts, images, producers, owners, patrons, places, devotions, and the relations between all of these aspects - over a long period of time by combining quantitative network analysis with advanced qualitative analysis to reach meaningful interpretations of the data.The nature of the material requires this research to be tackled within a multidisciplinary project. All members contribute to the digital network analysis. Sections of the ecosystem are further analyzed in work-packages that focus on the production and reception of manuscripts, the poetics of prayer, the function of images, and changes and continuities in relation to religious movements and the advent of print. The project will yield an integrative understanding of the role of prayer books in the late medieval Low Countries on the threshold of the medieval and early modern era.