This volume offers the first book-length study in English of the life and work of the Early Modern mystical author Maria van Oisterwijk (+1547). It provides a detailed study of her remarkable life, which is discussed in its broader religious and historical context, her extensive spiritual network that included the Cologne Carthusians and the early Jesuits, and her mystical works, offering extensive quotations that are available here in English translation for the first time. In the final chapter, Maria of Oisterwick's mystical spirituality is placed in the broader context of the development of the mystical tradition in the Low Countries and its echoes in mystical writings up to the present day.