The Reformation in Sweden was at least partly born in Storkyrkan: it was here that Lutheranism was publicly preached for the first time in Sweden and Storkyrkan was at the same time the first church in Sweden where Mass was celebrated in Swedish (instead of Latin), in 1525. One of the main advocates of the Reformation in Sweden, Olaus Petri, then served as a priest in Storkyrkan. As Storkyrkan from then on was used exclusively by the Swedish-speaking congregation of Stockholm, the sizeable German and Finnish-speaking congregations also moved out to the German Church and a chapel in the town hall, respectively.