delivered the opinion of the Court.
In this case, we are asked to decide the enforceability of an employer’s alleged promise to pay five percent of the proceeds of a sale or merger of the company to employees who are still employed at the time of the sale or merger. The employer, American Energy Services (AES), argues that because these were at-will employees, any promise was illusory and therefore not enforceable — the company could have avoided the promise by firing the employees at any time. The employees respond that the promise represented a unilateral contract, and by staying on with the company until AES Acquisition, Inc. acquired AES several years later, they performed on the contract, making it enforceable. We agree with the employees; continuing their employment with the company until it was sold would constitute performance under such a unilateral contract, making the promise enforceable, regardless of whether that promise may have been considered illusory at the time it was made. We therefore reverse the court of appeals’ judgment and remand the case to the trial court to consider the merits.
I
AES was formed in the summer of 1996. AES hired the petitioners in this case (collectively, the employees) that same year. The employees allege that in an operational meeting in June 1997, they voiced concerns to John Carnett, a vice president of AES, about the continued viability of the company. The employees complained that the company required them to work long hours with antiquated equipment. The employees allege that, in an effort to provide an incentive for them to stay with the company, Carnett promised the employees, who were at-will and therefore free to leave the company at any time, that “in the event of sale or merger of AES, the original [eight] employees remaining with AES at that time would get 5% of the value of any sale or merger of AES.” AES Acquisition, Inc. acquired AES in 2001. Seven of the eight original employees were still with AES at the time of the acquisition. Those remaining employees demanded their proceeds, and when the company refused to pay, the employees sued, claiming AES breached the oral agreement.
AES moved for summary judgment on two grounds: that the agreement was illusory and therefore not enforceable, and that it violated the statute of frauds.
1
The employees responded that the promise represented a unilateral contract, and by remaining employed for the stated period, the employees performed, thereby making the promise enforceable. The trial court
*301
granted AES’s motion for summary judgment, and the employees appealed. The court of appeals affirmed, holding that the alleged unilateral contract failed because it was not supported by at least one non-illusory promise, citing this Court’s decision in
Light v. Centel Cellular Co. of Texas,
II
AES argues, and the court of appeals held, that our holdings in
Light,
Consideration for a promise, by either the employee or the employer in an at-will employment, cannot be dependent on a period of continued employment. Such a promise would be illusory because it fails to bind the promisor who always retains the option of discontinuing employment in lieu of performance. When illusory promises are all that support a purported bilateral contract, there is no contract.
Light
involved an employee’s challenge to a covenant not to compete.
Id.
at 643. Approximately two years after being hired, Light, an at-will employee, executed a covenant not to compete with her employer.
Id.
Relying on the Covenants Not to Compete Act, Tex. Bus.
&
Com.Code § 15.50(a), the employer, United Telespectrum, sought to enforce the covenant against Light after she left the company.
Id.
The Act provides that “a covenant not to compete is enforceable if it is ancillary to or part of an otherwise enforceable agreement at the time the agreement is made.” Tex. Bus. & Com.Code § 15.50. We held that “[although Light and United did have an otherwise enforceable agreement between them, the covenant was not ancillary to or a part of that otherwise enforceable agreement.”
Light,
We revisited the issue of illusory promises in covenants not to compete in
Shesh-unoff.
In that case, an employer again sought to rely on the Covenants Not to
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Compete Act to enforce a covenant against a former employee.
Citing our holdings in
Light
and
Sheshunoff,
the court of appeals stated that “[a] unilateral contract may be formed when one of the parties makes only an illusory promise but the other party makes a non-illusory promise. The non-illusory promise can serve as the offer for a unilateral contract, which the promisor who made the illusory promise can accept by performance.”
The issue turns on the distinction between bilateral and unilateral contracts. “A bilateral contract is one in which there are mutual promises between two parties to the contract, each party being both a promisor and a promisee.”
Hutchings v. Slemons,
The court of appeals held that even if AES promised to pay the employees the five percent, that promise was illusory at the time it was made because the employees were at-will, and AES could have fired all of them prior to the acquisition.
Furthermore, the court of appeals’ holding would potentially jeopardize all pension plans, vacation leave, and other forms of compensation made to at-will employees that are based on a particular term of service. Corbin on Contracts observed as much in discussing the court of appeals’ opinion in this case:
The court’s analysis may attempt to prove too much. The argument that a promise to grant a raise to a terminable-at-will employee is necessarily illusory raises the question, why is an employer’s original promise to pay a certain wage to an at-will employee enforceable when the employee performs? The court’s analysis would suggest that the employer’s promise was never enforceable. If an at-will employee is hired at a promised compensation and performs for *304 some period, the court’s analysis would suggest, that the promised rate of compensation-was never enforceable.
1 John E. MurRay, Jr. s Timothy Murray, Corbin on Contracts § 1.17 (Supp. Fall 2009). We agree that the court of appeals’ opinion could have far-reaching adverse effects on well-established forms of compensation.
The fact that the employees were at-will and were already being compensated in the form of them salaries in exchange for remaining employed also does hot make the promise to pay the bonus any less enforceable.
It is now recognized that these are not pure gratuities but compensation for services rendered. The employer’s promise is not enforceable when made, but the employee can accept the offer by continuing to serve as requested, even though the employee makes no promise. There is-no.mutuality of obligation, but there is consideration in the form of service rendered. The employee’s one consideration, rendition of services, supports all of the employer’s promises, to pay the salary and to pay the bonus.
2 Corbin on Contracts § 6.2;
see also
Elizabeth T. Tsai, Annotation,
Promise By Employer to Pay Bonus as Creating Valid and Enforceable Contract,
Ill
AES allegedly promised to pay any remaining original employees five percent of the proceeds when AES was sold. Assuming AES did make such an offer, the seven remaining employees accepted the offer by staying with AES until the sale. Regardless of whether the promise was illusory at the time it was made, the promise became enforceable upon the employees’ performance. The court of appeals erred in holding otherwise. Accordingly, we reverse the' court of appeals’ judgment and remand the case to the trial court for further proceedings consistent with this opinion. Tex. R.App. P. 60.2(d).
Notes
. AES has since expressly abandoned its statute of frauds defense. See Tex. Bus. & Com.Code § 26.01(b)(6).
. In fact, Williston on Contracts disapproves of the use of the term "unilateral contract" to describe an agreement in which one of the promises in a bilateral contract fails:
[T]he term unilateral contract should be reserved for cases in which a legal obligation has been created, but only one party to the obligation has made a promise. When there is no obligation, the transaction may be a unilateral promise or a unilateral
offer, but it cannot properly be called a unilateral contract. Thus, for example, when the promisor seeks a return promise and obtains an illusory promise, his or her own undertaking may properly be characterized as unilateral; but since no enforceable obligation exists, it is not properly called a unilateral contract.
1 Williston on Contracts § 1.17.
