The Marburg Colloquy was a meeting at Marburg Castle, Marburg, Hesse, Germany, which attempted to solve a disputation between Martin Luther and Ulrich Zwingli over the Real Presence of Christ in the Eucharist. It took place between 1 October and 4 October 1529. The leading Protestant reformers of the time attended at the behest of Philip I of Hessen. Philip's primary motivation for this conference was political; he wished to unite the Protestant states in political alliance, and to this end, religious harmony was an important consideration.
After the Diet of Speyer had confirmed the edict of Worms, Philip I felt the need to reconcile the diverging views of Martin Luther and Ulrich Zwingli in order to develop a unified Protestant theology. Besides Luther and Zwingli, the reformers Stephan Agricola, Johannes Brenz, Martin Bucer, Caspar Hedio, Justus Jonas, Philip Melanchthon, Johannes Oecolampadius, Andreas Osiander, and Bernhard Rothmann participated in the meeting.
If Philip wanted the meeting to be a symbol of Protestant unity he was disappointed. Luther and Zwingli fell out over the sacrament of the Eucharist.