In the wake of the passing of John W. O’Malley, SJ, one of the greatest church historians of our time, the journal invited Massimo Faggioli to reflect on O’Malley’s contribution to contemporary theology. Analyzing his major works on Vatican II and ecclesiology—in particular, What Happened at Vatican II—Faggioli argues that O’Malley perceived a new phase in the history of the hermeneutics of the council and responded with a historicization of the conciliar tradition between Trent and Vatican I.