This book examines the early development of the Reformation debate over the Lord's Supper. Going beyond Martin Luther and Ulrich Zwingli, it demonstrates the importance of late medieval heresy and the key role played by Andreas Bodenstein von Karlstadt in challenging traditional belief in Christ's corporeal presence in the sacrament. The book is a very successful invocation of the flux and fluidity of this early debate, a work of careful scholarship and broad learning that represents a lasting contribution to Reformation history.