Proponents of foreign-led state building or shared sovereignty arrangements have exaggerated the ability of powerful states to foster institutions in developing countries. The empirical record, from successful outcomes in Germany and Japan to dismal failures across the global South, shows foreign forces are heavily constrained by antecedent local capacity. The societies alleged to be most in need of strong institutions have proven the least tractable for foreign administration. Rather than transmitting new modes of organization, would-be state builders have relied upon existing structures for governance. This dependence on the very context that was intended for change shows that foreign state builders wield very little infrastructural power. They are consistently unable to implement political decisions through the subject population. Contrary to recent arguments that sustained effort and area expertise can enable success, external state building has foundered despite such investments. Understanding why foreign-led state building continues to fail is crucial for redirecting intervention where it can be more effective. Advocates of humanitarian assistance should consider the merits of smaller, regenerative projects that can respond better to uncertainty and avoid the perils of large-scale political engineering.