The regulation of theology in the Reformation era took many forms. Among the factors that shaped the procedures were the practices of the ancient and medieval church, the particular ecclesiology and polity adopted by various denominations and the authority they gave to their church officials and to new institutions, their credal statements, and the wishes of the Christian rulers in whose territories they functioned.

Most histories of Reformation-era theology have been organized either by theologian or by subject. Both approaches follow a straightforward logic, but they also have limitations, and these have become more evident as the field has expanded and become more complex. Works that treat theology as products of individual minds tend to overlook the role of dialogue and collaboration, mutual influences, and academic exchange in the generation of ideas. That is especially problematic for an era that was shaped by the emergence of new religious communities and confessional identities, powerful currents of polemic and controversy, and strategies for conflict resolution – none of which are given adequate account by viewing individual theologians in isolation. Organizing a history of theology by subject, that is, according to a list of prominent theological topics, solves some of the problems of the first approach but introduces a different set of deficits.

The introductory chapter surveys the events that led to the convocation of the Council of Trent and summarizes what was accomplished at each of its twenty-five sessions. It also recounts how its was formally approved, its decrees published, their interpretation and implementation entrusted to the Congregation of the Council, and its legislation promulgated by provincial councils. How the council has been remembered by historians and its records made available is also traced.

The council both followed precedents and created new ways of managing its affairs. It abandoned the “nations” and deputation structures of Konstanz and Basel in favor of classes, particular congregations of “minor theologians,” and congregations of prelate-theologians and of prelate-canonists, while retaining the general congregatons andformal sessions. Papal legates, whose powers increased with time, determined the agenda and presided over the proceedings. An effort is made to determine the numbers and nationalities of the participants for each of the three periods. The reasons for the failed participation of Protestants and Eastern Christians are explored.