Classical contract theory rested on a deceptively simple premise: a promise becomes legally enforceable only when it is exchanged for consideration - something bargained for and given in return. Under this bargain model, a gratuitous promise, however solemn, imposed no obligation, because the promisee had surrendered nothing in exchange. The doctrine served an evidentiary function, marking which commitments the parties intended to be binding, and a cautionary one, impressing on promisors the gravity of their undertaking. Yet by the early twentieth century, courts confronted a recurring difficulty: promisees who had reasonably relied on a promise, altering their position to their detriment, found themselves without remedy whenever the promise lacked a bargained-for return. The doctrine of promissory estoppel emerged to fill this gap. As later codified in influential treatises, it provides that a promise which the promisor should reasonably expect to induce action or forbearance, and which does induce such action, is binding if injustice can be avoided only by enforcement. Critics initially dismissed estoppel as a mere gloss on consideration, a way of smuggling reliance into a doctrine officially indifferent to it. Its defenders, however, insisted that estoppel rested on a wholly distinct principle: not the enforcement of bargains, but the protection of justified reliance and the prevention of harm the promisor had foreseeably caused. The distinction matters, and not merely taxonomically. If estoppel is a species of consideration, the remedy should be the same as for breach of any contract - the promisee's full expectation, measured by the value of the promise as if performed. But if estoppel instead protects reliance, the appropriate remedy may be narrower: restoration of the promisee to the position occupied before the promise was made, compensating the detriment incurred rather than the expectancy defeated. Several courts, recognizing this, have limited recovery under estoppel to reliance damages, awarding less than a conventional breach would yield. This is where the doctrine's success has bred a fresh conceptual instability. Precisely because estoppel enforces promises without bargained-for exchange, some commentators have proclaimed the death of consideration, arguing that reliance has quietly become the true basis of promissory liability. The claim overstates. Estoppel remains, in most jurisdictions, an exceptional route to enforcement, available only where reliance is both reasonable and substantial and where the equities are compelling; the ordinary commercial promise still travels the well-worn road of bargain. What estoppel has accomplished is subtler: it has exposed that consideration was never a unitary principle but a bundle of functions - evidentiary, cautionary, channeling - which reliance can sometimes discharge and sometimes cannot. To announce that one has displaced the other is to mistake a supplement for a substitute. The more defensible conclusion is that Anglo-American contract law now rests on two grounds of obligation, uneasily coexisting, each incomplete without the other, and that the persistent effort to reduce them to a single principle has obscured more than it has clarified.