At first glance, investigating the uniformity of churches and religious groups seems like a dead-end, rather than a “Pathway Through Early Modern Christianities”. Recent scholarship has revealed, after all, that concepts like polycentricity and plurality are better tools for navigating early modern religious landscapes than unity and uniformity. Yet is uniformity simply the opposite of polycentricity and plurality, or is it a richer concept? This talk distinguishes, first, between formal-institutional centrality and functional-substantive homogeneity. The Tridentine Reforms offer a valuable case study for understanding the complex and even dialectical relationship between both dimensions of uniformity. That Roman bureaucracy in many respects generally forwent homogenisation does not present a conclusive argument against uniformity. To the contrary, the centrality of the early modern papacy depended on it.