John O’Malley’s Trent: What Happened at the Council offers English-speaking audiences the first concise and scholarly history of the council that did much to shape the modern Catholic Church. O’Malley’s narrative of the Council of Trent (1545–47, 1551–1552, 1562–1563) masterfully explains it as more than a series of theological debates, contextualizing it in terms of the Protestant Reformation, international politics and rivalries (including among Catholic princes), and conciliarism and papal authority. Its decrees, centered on the twin pillars of reform and doctrine, clarified dogma in the face of Lutheran challenges and redefined bishops’ chief responsibility as the care of souls. O’Malley’s interpretation of the council historicizes doctrine (which can easily appear as timeless), gives its decrees the context needed to understand them beyond face value, and distinguishes between what was the work of the council and what were later interpretations of its work. Although O’Malley presents the council as a European phenomenon, its effects were more global. A case study from colonial Mexico helps reveal how Trent’s strengthening of episcopal authority but unwillingness to address the issue of papal privilege created the space for conflict, in this instance between a bishop seeking to expand his powers and Mendicants seeking to limit his authority. How such conflicts were resolved depended on local circumstances as well as the individuals and groups involved. In this case, the Spanish monarchy’s support for bishops and the decrees of Trent over regular clergy and papal privilege proved the crucial factor.