What are the stakes in distinguishing between gifts and contracts, between gratuitous undertakings and those supported by consideration? This Article addresses the effects of the distinction by comparing early debates over the doctrine of consideration with recent debates over the law of gifts. Late nineteenth-century legal scholars revolutionized the doctrine of consideration, unifying diverse doctrines around the single question of the enforceability of promises. But while the revolution in consideration doctrine succeeded in generating widely agreed upon rules, a detailed examination of case law surrounding gift promises shows that the rules could not ensure predictable outcomes even in what should have been easy cases. Twentieth-century changes in the rules and their justifications left the framework for discussion intact, and have not challenged the conception of contract as centered on promissory liability. This Article argues that placing the question of consideration at the heart of contract theory is the technical manifestation of a conceptualization of contract around promise, rather than around more diffuse ideas of obligation. By placing promise at the center of contractual obligation, consideration theory advances a conception of contracting individuals as knowing and willful, as taking on obligations in measured, calculable increments, exchanging their obligations for precise values. By establishing the calculating individual as the sole source of obligations, the theory submerges the role of the state in determining the content of parties' obligations, and works a subtle delegitimation of state power over such obligations.