Unilateral Contract

In one sentence

A contract where only one party makes a binding promise in exchange for the other's performance.

Plain English

A unilateral contract is a one-sided deal where one party makes a promise, and the other party accepts by actually performing the requested action rather than by making a return promise. The person making the offer doesn't require a promise back—they just want the action done. Once the other party starts performing, the offeror becomes bound, but the performer isn't bound until they actually complete the act.

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Example

You post a sign offering $500 to anyone who finds and returns your lost dog. A neighbor finds your dog and returns it. By performing the action, the neighbor accepted your offer and you're now bound to pay the $500. The neighbor didn't have to promise anything—just do it.

Used in a sentence

“The unilateral contract was formed when the employee completed the project as requested by the employer.”

Related terms

Bilateral Contract

A contract where both parties make binding promises to each other.

Express Contract

A contract where the parties clearly state all terms, either in writing or orally.

Mutual Assent

Both parties agree to the same contract terms at the same time.

Consideration Substitute

A replacement for the usual exchange of value needed to make a contract binding.

Revocation

An offeror's withdrawal of an offer before it's accepted, ending the power to form a contract.

Offer

A proposal to enter into a binding agreement on specific terms.

Acceptance

Agreeing to the exact terms of an offer, creating a binding contract.

Consideration

Something of value exchanged by each party to make a contract binding.

This page is a plain-English reference and is not legal advice. Laws vary by jurisdiction and change over time. For specific situations consult a licensed attorney.