Elector Johann of Saxony (1468–1532) is almost unknown for re­search on the history of the Reformation. New source finds prove that he had been intensely interested in Martin Luther and his ideas since 1520. Johann also influenced his brother Friedrich the Wise (1463–1525). Even before 1525, Thuringia, Johann’s dominion, had a Reformation landscape characterised by diversity. The article not only describes Johann’s commitment to the Reformation, but also attempts to describe his political measures and theological convictions in the tension between the Reformation being led by the authorities and being determined by the congregation. Thus the term »Fürstenreformation« is filled positively