Chevron Chemical Company appeals from a judgment entered on a jury verdict in a wrongful discharge action brought by an employee, John Stewart. The jury determined that Chevron had breached an employment contract with Stewart by failing to abide by a layoff provision in its policy manual. We hold the layoff policy was not a term of Stewart's contract and reverse.
Stewart began employment with Chevron Chemical Company in 1954 pursuant to an oral agreement for an indefinite term. From 1959 until his termination he worked as a shift supervisor in Chevron's fertilizer production plant near Kennewick. Due to financial losses in its fertilizer division, Chevron management implemented a reorganization program in 1983 which included reducing the number of shift supervisors at the Kennewick plant from twelve to eight. Several Kennewick supervisors who had accrued the most seniority had the lowest performance rating. Since the responsibilities of the eight remaining supervisors would be significantly increased, Chevron decided to retain its best performers and based layoffs on the preceding 3 years' performance evaluations rather than on length of service. Stewart had the most seniority but the lowest performance rating and was one of the four discharged.
Stewart unsuccessfully appealed his termination through company grievance procedures. He then brought suit for wrongful discharge based on three grounds: (1) lack of just *611cause; (2) age discrimination; and (3) breach of his employment contract by Chevron's failure to follow applicable termination procedures. The trial court determined Stewart's employment contract did not require just cause for termination and granted Chevron partial summary judgment on that issue. The jury ultimately found Stewart's discharge was not based on age discrimination. Stewart has not appealed either of these decisions; thus, the sole issue remaining is whether Chevron was contractually required to follow certain procedures prior to discharging Stewart.
Stewart based his breach of contract claim on § 380 of Chevron's policy manual, which states:
In determining the sequence of layoffs due to lack of work, consideration should be given to performance, experience and length of service.
Stewart claims that this provision was an implied term of his employment contract requiring that he be discharged only after consideration of all three factors, and that Chevron breached the contract by terminating his employment solely because of his poor past performance.
At the close of Stewart's case and after presentation of all the evidence, Chevron unsuccessfully moved for a dismissal and a directed verdict on the grounds that the layoff provision was not a specific promise and that the policy manual provisions were not generally disseminated or communicated to employees. The trial court ruled as a matter of law that the language of § 380 constituted a promise of specific treatment and submitted to the jury the issue of whether that policy was part of Stewart's employment contract.
The jury found that Chevron had breached the employment contract based on § 380 and awarded $380,000 in damages. Chevron's motions for a judgment notwithstanding the verdict or in the alternative for a new trial were denied. Chevron appealed. We accepted direct review.
Stewart relies on Thompson v. St. Regis Paper Co., 102 Wn.2d 219, 223, 685 P.2d 1081 (1984), in support of his claim that Chevron's layoff policy became a binding *612term of his contract. Generally, an employment contract indefinite in duration may be terminated at any time by the employee or the employer, with or without cause. Roberts v. ARCO, 88 Wn.2d 887, 891, 568 P.2d 764 (1977); Webster v. Schauble, 65 Wn.2d 849, 852, 400 P.2d 292 (1965). In Thompson, however, this court held that a terminable-at-will relationship may be modified and the employer contractually bound by promises of specific treatment made in employee manuals or handbooks. The court reasoned that established personnel policies may, in certain circumstances, create legitimate employee expectations that the policies will be binding.
It would appear that employers expect, if not demand, that their employees abide by the policies expressed in [employee] manuals. This may create an atmosphere where employees justifiably rely on the expressed policies and, thus, justifiably expect that the employers will do the same. Once an employer announces a specific policy or practice, especially in light of the fact that he expects employees to abide by the same, the employer may not treat its promises as illusory.
Thompson, at 230. Therefore, the court held:
[I]f an employer, for whatever reason, creates an atmosphere of job security and fair treatment with promises of specific treatment in specific situations and an employee is induced thereby to remain on the job and not actively seek other employment, those promises are enforceable components of the employment relationship. We believe that by his or her unilateral objective manifestation of intent, the employer creates an expectation, and thus an obligation of treatment in accord with those written promises.
Thompson, at 230. See also Brady v. Daily World, 105 Wn.2d 770, 774, 718 P.2d 785 (1986).
Chevron initially contends its policy manual was not part of the employment contract as it was a policy guide for management and was not communicated to employees. The jury was presented with conflicting evidence on this issue. We need not decide whether substantial evidence exists to *613support the jury's finding that the policy manual was binding as we find that the trial court initially erred in ruling that the layoff provision constituted a promise of specific treatment in a specific situation.
The interpretation of a writing is a question of law for the court. In re Estate of Larson, 71 Wn.2d 349, 354, 428 P.2d 558 (1967); 4 S. Williston, Contracts § 616, at 649 (3d ed. 1961). Only those statements in employment manuals that constitute promises of specific treatment in specific situations are binding. Thompson, at 230. As the Thompson court noted, "policy statements as written may not amount to promises of specific treatment and merely be general statements of company policy, and thus, not binding." Thompson, at 231. The Restatement (Second) of Contracts defines a promise as
a manifestation of intention to act or refrain from acting in a specified way, so made as to justify a promisee in understanding that a commitment has been made.
(Italics ours.) Restatement (Second) of Contracts § 2 (1981). Accord, 1 A. Corbin, Contracts § 13 (1963). A supposed promise may be illusory if it is so indefinite it cannot be enforced or if its performance is optional or discretionary on the part of the promisor. Spooner v. Reserve Life Ins. Co., 47 Wn.2d 454, 458, 287 P.2d 735 (1955); Sandeman v. Sayres, 50 Wn.2d 539, 541, 314 P.2d 428 (1957); Goodpaster v. Pfizer, Inc., 35 Wn. App. 199, 203, 665 P.2d 414 (1983).
Chevron's layoff policy states only that management "should" consider performance, experience and length of service in determining the sequence of layoffs. This does not create an obligation that Chevron will or must consider all three factors. "Should" may be interpreted as discretionary, indicating merely a recommendation or preference. See Cuevas v. Superior Court, 58 Cal. App. 3d 406, 409, 130 Cal. Rptr. 238 (1976); University of South. Fla. v. Tucker, 374 So. 2d 16 (Fla. Dist. Ct. App. 1979); Magnuson v. County of Grand Forks, 97 N.W.2d 622, 624 (N.D. 1959). Throughout other portions of the manual Chevron used the *614terms "shall", "will" and "must", but in the layoff provision used "should", indicating Chevron intended that the provision be advisory. See Magnuson, at 624.
Furthermore, Chevron was only required to "consider" these factors; no relative weight or value is assigned to any of the criteria. Thus, even if Chevron had factored Stewart's length of service into its decision, it was not required to give that criterion more weight than performance, or any weight whatsoever if management deemed it inadvisable to do so. Thus the wording of § 380 does not set forth the specificity necessary to create a binding promise. In addition, Chevron's human resources manager, who formulated the severance plan for the fertilizer division, testified that he initially ranked the Kennewick supervisors according to their length of service but found that if seniority was used as the criteria for retention, several of the remaining supervisors would be the lowest performers. Therefore, Chevron management decided to use performance as the determining factor. The layoff policy was not a definite promise or commitment that Chevron would give more weight to seniority, as Stewart appears to argue, but was merely a guideline for management.
Further, we find no evidence that Stewart was aware of or relied on the layoff provision and was thereby induced to remain employed with Chevron. An employer is bound only by promises upon which the employee justifiably relied. Thompson, at 231, 233. Stewart testified he consulted the manual on several occasions to see what his rights were. He also testified that in 1967 or 1968 he turned down a job offer in reliance on the security of the policy manual claiming that the manual provisions provided job security. There is no evidence, however, that Stewart was aware of the company's layoff policy until after he was discharged. Stewart concedes this fact in his brief.
We conclude that Chevron's layoff policy was not part of Stewart's employment contract as the layoff policy was not a specific promise, and the policy was not relied on by Stewart.
*615Chevron raises additional assignments of error. Because of our holding, we need not address these other issues.
The judgment is reversed.
Utter, Brachtenbach, Dolliver, Andersen, and Durham, JJ., concur.