Abstract This article studies the mission of French Discalced Carmelite friars in the seventeenth-century Dutch Republic. Established from 1647 onwards in The Hague, Leiden, and Amsterdam, the missionaries’ aim was to minister to the French-speaking Catholics of Holland, but they also sought to convert expatriate French Protestants as part of the wider Counter-Reformation campaign to win back souls lost to the Reformation. Despite conflict with the Walloon churches, however, the Carmelite mission was surprisingly successful in converting Huguenots to the Church of Rome, repatriating many of them to France in the wake of the Revocation. As such, this article sheds new light on the relationship between expatriate communities in Holland, arguing that the Dutch Republic was not only a safe haven for refugees, but also the scene of ongoing conflict between French Protestants and Catholics during the reign of Louis XIV .