["Law & Society Review, Volume 55, Issue 1, Page 177-202, March 2021. ", "\nThe major aim of this article is to examine how migrations affect private governance, taking as a case study the Prud'homie de pêche, a private order that has governed the fishery of Marseille for the past six centuries. Scholarship generally argues that social norms guarantee the efficiency of private orders and their ability to resist the arrival of newcomers. My data suggest that the Prud'homie has failed to accommodate social changes prompted by migratory flows, not despite but because of its social norms. This paper suggests that social norms are not only powerful tools of governance for private orders, but also forces of inertia that can prevent these orders from accommodating social changes.\n"]