This article argues that Modernism was the pivotal “ghost” at Vatican II. Evocations of Modernism and anti-Modernist doctrinal documents on the council floor were numerous and often heated. Such evocations occurred in virtually every debate where the development of doctrine was at stake. The council majority’s dismissal, indeed rejection, of the anti-Modernist paradigm constituted a kind of revolution of theological methodology. Understanding how anti-Modernist doctrinal documents were evoked at Vatican II sheds important light on the council and its achievements, compromises, and failures.