This is the first published monograph on Claude Pajon (1626-1685), the theologian at the origin of the greatest doctrinal controversy within the French Protestant camp in the mid to late seventeenth century. Drawing on manuscript sources, this study examines Pajon’s thought and its origins, and traces the nature and course of the first phase of controversy (1665-1667). It demonstrates that the conflict opposed Pajon as a ‘radical’ Cameronian over against the ‘moderates,’ with each party claiming to represent the true theological heritage of John Cameron (ca. 1579-1625), as proposed by Paul Testard (ca. 1596-1650) and Moïse Amyraut (1596-1664), respectively. The result is a new look on the theology of the academy of Saumur, and on the history of this institution.