Secessionist movements are ubiquitous in the Caribbean, with virtually every multi-island state and territory experiencing centrifugal tendencies. The region thus offers a unique opportunity to examine why some succeed and others fail. By and large, the propensity for secession has not attracted the attention of scholars beyond the region, with small states and territories largely excluded from supposedly ‘global’ analysis on the subject. The article fills this gap by analysing secessionist movements in both sovereign and non-sovereign territories. We find that secession was most likely to occur in the run-up to independence. In the post-colonial period, successes have only occurred among non-sovereign territories—as demonstrated by the fragmentation of the Netherlands Antilles and the administrative separation of St Martin and St Barthélémy from Guadeloupe—which have split from each other while collectively remaining part of a metropolitan state. Non-sovereignty reduces the costs of heterogeneity via the shelter provided by the larger metropolitan power. By analysing hitherto understudied cases, this article thus adds to studies that show how secession is contingent on continued state protections which allow downsizing to occur in an orderly manner, which is in turn consistent with the desire of the international community for geopolitical stability.