The Echelles du Levant et de Barbarie were French trading centers across the Ottoman Empire that were granted special trading privileges by the sultan. Naturally, their center was in Istanbul, where hundreds of French merchants carried out a large volume of trade across the Mediterranean. In 1781 those merchants wrote to their government to criticize the tight restrictions placed on their everyday life and trade by a new regime of regulation. Their protest revealed the currency of a new idea of the plastic and adaptable human subject, shaped by the cultural environment rather than by innate qualities: a kind of "cosmopolitan subject" that we may associate with Enlightenment thought. But they employed this conception in order to raise the specter of an "infection" spread by such adaptation, necessitating the exclusion of foreigners, and above all the subjects of the sultan, whether Jewish, Christian, or Muslim, from commercial activity between Istanbul and Marseille. Their protests were ultimately successful in scuttling the French government's nascent free-trade policies in regard to the Levant. This article suggests that the legislative activity of the French state intersected in particular ways with ideas about cosmopolitanism over the course of the eighteenth century in the reconstruction of the nature of everyday life for the "Franks" of the Echelles. It investigates how these converging processes worked to dismantle the older Levantine or "Eurasian" cosmopolitanism that had been for centuries the basis for coexistence under Ottoman rule.