Between 1538 and 1545, Wittenberg printer-publisher Georg Rhau published fifteen impressive liturgical-musical collections designed for worship needs of Lutheran congregations throughout the year. Friedrich Blume characterized Rhau’s effort as international in musical style and interconfessional in theology, but in fact, Rhau’s collections favored an outmoded, conservative cosmopolitan musical style that continued to enjoy popularity in Germany. Moreover, Rhau’s liturgical texts had to pass tests of scriptural authenticity and evangelical doctrinal orthodoxy in conformity with prevailing doctrines at Wittenberg that were subject to ongoing debates within Luther’s own circle. Leo Schrade, meanwhile, argued that the prefaces to Rhau’s collections proclaimed a Protestant theology of church music, but in fact, the lofty, expansive theology of music proclaimed in the prefaces to Rhau’s collections conflicted with the teachings of Zwingli and Calvin as much as with Catholic doctrine. Thus Rhau’s Lutheran collections contributed significantly to an early phase of the confessionalization of Europe.