Was Christ's human nature fallen, even sinful? From the 18th century to the present, this view has become increasingly prominent in Reformed theological circles and beyond, despite vigorous opposition. Both sides on the issue see it as vital for understanding the nature of salvation. Each side's advocates appeal to or critique the Church Fathers. This book reviews the history and present state of the debate, then surveys the connections, distinctions, and patristic interpretations of five of the modern fallenness view's proponents (Edward Irving, Karl Barth, T. F. Torrance, Colin Gunton, and Thomas Weinandy) and five of its opponents (Marcus Dods the Elder, A. B. Bruce, H. R. Mackintosh, Philip Hughes, and Donald Macleod). The book verifies the views of the ten most-cited Fathers: five Greek (Irenaeus, Athanasius, Gregory Nazianzen, Gregory Nyssen, and Cyril of Alexandria) and five Latin (Tertullian, Hilary of Poitiers, Ambrose, Augustine, and Leo the Great). The study concludes by sketching the implications of its findings for the doctrines of the Immaculate Conception, sin, sanctification, and Scripture.