The Genevan Reformation was subjected to a trenchant ethical critique during the sixteenth and seventeenth centuries by Roman Catholics, Lutherans, Anabaptists, and Radicals who identified both Calvin and Beza as unscrupulous, dishonest, and immoral. By contrast, modern scholars have paid little attention to such matters. They have either stated explicitly that both men were upright and honest in their lives and ministries or implied it. A handful of scholars have, however, alluded to dishonest conduct on their parts. The present article takes up this topic in detail, looking particularly at Geneva's ministry to France. It contends that duplicity characterized Calvin and Beza's French ministry between 1536 and 1563. It commences by examining their understanding of mendacity, which provides the standard for our analysis of their ministry. After outlining what Calvin and Beza did to support and strengthen Calvinist churches in France, the article sets forth and explains the system Calvin devised to hide their ministry from the French Catholic government and probably from the Nicodemites as well. This system depended on lies, deceit, and simulation.