In a __________, only one party is legally obligated to perform.

A unilateral contract is defined as a type of agreement in which only one party makes a legally enforceable promise or commitment to perform a service or task. This means that one party is obligated to take action, while the other party does not bear any corresponding duty to perform in return. A common example of a unilateral contract is a reward offer, where one party promises to pay a reward to anyone who finds and returns lost property; the person returning the property is not obligated to do so, but if they take action, the offeror must fulfill their promise.

This structure is what distinguishes unilateral contracts from other types, where mutual obligations are typically present. In contrast, conditional contracts involve terms that depend on the occurrence of a specific event, contracts of adhesion are those where one party has significantly more power in drafting the terms, and contracts of utmost good faith require both parties to act honestly and transparently. Therefore, the defining trait of a unilateral contract is the one-sided obligation to perform.