Moral cosmopolitans are committed to the claim that all human beings hold equal status as the fundamental units of moral concern and should thus be extended equal concern and respect by all other human beings. Cosmopolitans often argue that this claim implies a cosmopolitan institutional scheme; that is, institutional arrangements that include at least some supra-state institutions that have global jurisdiction with respect to some issues and are granted authority to legitimately constrain the activity of states in pursuing those objectives in service of cosmopolitan objectives. Contrary to this, I argue that cosmopolitan moral commitments have important statist institutional implications. In general, this is a familiar refrain; e.g., Blake (2001) and Sangiovanni (2007) argue that cosmopolitan moral commitments entail limiting the scope of distributive justice to states, while Goodin (1988) and Ypi (2008) argue that certain instrumental considerations imply that cosmopolitan moral objectives are most effectively realized by a system of states. Diverging from extant offerings, I argue instead that cosmopolitan institutional arrangements are self-defeating in certain important cases. Successful economic and political development occurs when a state's institutions restrain rulers' from predatory behaviour and compel them to provide public goods, such as rule of law, public infrastructure, and investment in human capital. Extending work by, among others, Bates and Lien (1985) and Tilly (1990), I argue that this occurs wherever two conditions are met: first, state rulers depend on the cooperation of some citizens to pursue the former's objectives (e.g., to remain in office); second, the citizens on whose cooperation the ruler depends have credible "exit options", that is, they can withhold their cooperation without making themselves worse off than they would be were they to cooperate with the ruler. Given this explanation of development, I argue that certain cosmopolitan arrangements undermine rulers' dependence on citizens -- thus stifling successful development -- whereas preserving a system of sovereign states maintains these conditions. This is significant because successful development is the most effective means for actually realizing the cosmopolitan's objective, viz., to protect people's rights and increase their well-being. The upshot is that those who hold cosmopolitan moral commitments should endorse a system of states for pragmatic reasons.