"The article addresses a two-fold question: first, why does the French state invest so much time and resources in its Indian Ocean islands, Mayotte and Réunion? And why do these ultra-marine regions remain wedded to the French Republic? The high degree of insular buy-in both regions involves a two-level game, connecting state and island actors. Such turning to mainland France represents a form of African agency, however dependent on the mainland these islands appear to be. The causal mechanisms of the integration of the French Indian Ocean territories combine historical legacy (choosing France), institutional evolution (departmentalisation), common economic and military security challenges, the cost calculus of mainland France’s readiness to govern ultramarine territories and a widely shared set of beliefs in the value of remaining French. The islands are acting like rational actors, whose insular and isolated status pushes in the direction of seeking protection in an unstable environment."