This book explores the origins and development of one of the most significant doctrines of Reformation theology. The innovative ways in which the Zurich reformer Huldrych Zwingli and his successor Heinrich Bullinger thought about the relationship between the Old and New Testaments left an indelible mark on the Reformed tradition in the sixteenth and seventeenth centuries. Distinctively, Zwingli and Bullinger emphasized the continuity of both testaments and spoke of a single covenant between God and humanity. This would become one of the defining teachings of Reformed Christianity. This book follows the development of their covenant theology in the Reformation and argues for its adoption by John Calvin in Geneva and the German theologians of the post-Reformation era.This book offers a fresh interpretation of covenantal theology in the Reformation by demonstrating how the writings of the Zurich reformers Huldrych Zwingli (1484-1531) and his successor Heinrich Bullinger (1504-75) decisively shaped a foundation of the Reformed tradition. The book overturns previous research that has both emphasized Zurich's irreconcilability with later developments of Reformed covenant theology and downplayed the contribution of the Zurich theologians in favor of figures such as Philipp Melanchthon (1497-1560) and John Calvin (1509-64). It argues for the dependence of Calvin and other leading figures on Zurich and for continuity in the later Reformed tradition with its origins in the 1520s.Pierrick Hildebrand demonstrates that the concept of a prelapsarian covenant, generally used as an argument for discontinuity between Zurich and Heidelberg, was clearly present in Zwingli and Bullinger. Further, Bullinger's covenantal terminology, which integrates the concept of the covenant with union with Christ, was adopted by Calvin and later by the Heidelberg theologians. Rejecting the idea that Zurich and Geneva represented two different traditions, Hildebrand details significant continuities l#[