The Swiss theologian Huldrych Zwingli (1484-1531) was one of the most prominent reformers and the founder of the Reformed Protestant Church in the Swiss Confederation. During the last hundred years more than 200 titles from his private library have been discovered. They give an interesting insight into his interests and sources. The present book contains not only an extensive introduction and a catalogue of these books and manuscripts, but also an inventory of the lost works possessed by Zwingli. They open the door to Zwingli's study and to the intellectual world of an important reformer.