This thesis investigates how religious coexistence functioned in the multiconfessional region of Upper Lusatia in Western Bohemia. Lutherans and Catholics found a feasible modus vivendi through written agreements and regular negotiations. This meant that the Habsburg king of Bohemia ruled over a Lutheran region. He knew of the situation in Lusatia but was not willing to intervene decisively to reintroduce Catholicism. Lutherans and Catholics in Upper Lusatia shared spaces, objects and rituals. Catholics adopted elements previously seen as a firm part of a Lutheran confessional culture. Lutherans, too, were willing to incorporate Catholic elements into their religiosity. Some of these overlaps were subconscious, while others were a conscious choice. Later generations of historians fashioned these complex processes of change into a neater Reformation narrative. This research provides a narrative of the Reformation in Upper Lusatia and engages with three historiographical paradigms. Firstly, the results show that the concept of the 'urban Reformation', where towns are seen as centres of Lutheranism has to be reassessed, particularly in towns in former East Germany, where much work remains to be done. Secondly, it shows that in a region like Upper Lusatia which did not have a political centre, undergoing a complex Reformation, there was no clear confessionalization process. As other studies have found similar tendencies elsewhere in the Holy Roman Empire, the usefulness of the confessionalization paradigm is increasingly questionable. Thirdly, the example of dissenting religious groups cautions us that it is not helpful to push the idea of toleration in early modern Europe too far. In the case of Upper Lusatia, the coexistence of two confessions, Lutherans and Catholics, meant that others were excluded.