This article examines the role played by Marie Petit (b. 1673) in the French diplomatic mission to Safavid Iran from 1706 to 1708. The paper situates her among the small group of French women who exercised diplomatic authority in the reign of Louis XIV and highlights the particular roles played by gender and religion in Petit’s arrest and incarceration. The article argues that while Petit’s gender and alleged sexually illicit behavior may have been used by her opponents as one of the main pretexts for incarcerating her, it was by no means unheard of for French women to exercise diplomatic authority under Louis XIV, and some of these women were similarly accused of illicit sexual behavior. In order to explain why French authorities were so hostile to Petit’s playing a leading role in the French diplomatic mission after the appointed envoy, Jean-Baptiste Fabre (ca. 1650–1706), died in Yerevan, the article emphasizes the perception among certain French authorities that Petit was threatening French interests in promoting Catholic missionary work in the Levant and in supporting the Uniate Armenian Christians against the “schismatic,” or Gregorian, Armenian Christians.