This article analyzes the different ways that clandestine marriages were reproved in the writings of reformists and for what purposes. Medieval doctors had already demonstrated that a clandestine marriage was morally bad and canonically prohibited, even if they had had to recognize its validity to strengthen the consensualist theory of sacrament. In order to prove marriage was an honorable way to salvation for the laity, the theologian Jean Raulin argued that clandestine marriages were as devilish as adultery or fornication. Erasmus reproved the troubles that arose from the validity of marriages contracted without family consent or by having sex after betrothal. The two of them wanted to defend the marriage sacrament and reorder society. But Erasmus's calling into question the sacramentality and indissolubility of clandestine marriages opened the way for Lutheran questioning of the scholastic theory of marriage: it is no sacrament but a civil contract, and parental approval is necessary to create it.