Karl Rahner had a pivotal influence on Vatican II during the preparatory phases, at the Council itself, and subsequent to the Council. This article asks how Rahner shaped the ecclesiology of the Council. It shows how many of the council’s emphases bear the hallmark of Rahner: the church as sacramentum mundi, the importance of the local church, the issue of collegiality, the church of sinners, and the priority of the pastoral. It will be argued that Rahner’s acute theological prescience in identifying issues facing the church into the future has been accurate and resonant with Pope Francis’s current project of ecclesial reform.