opinion: TRANS WORLD AIRLINES, INC. v. HARDISON et al.
  No. 75-1126.
  Argued March 30, 1977
  Decided June 16, 1977
  White, J., delivered the opinion of the Court, in which Burger, C. J., and Stewart, BlackmuN, Powell, RehNquist, and SteveNS, JJ., joined. Marshall, J., filed a dissenting opinion, in which BrenNan, J., joined, post, p. 85.
  George E. Feldmiller argued the cause for petitioner in No. 75-1126. With him on the brief was Dick H. Woods. Mozart G. Ratner argued the cause for petitioners in No. 75-1385. With him on the briefs were Plato E. Papps and Michael D. Gordon.
  William F. Pickett argued the cause for respondent Hardison in both cases. With him on the brief was Thomas L. Hogan.
  Nathan Lewin argued the cause for the National Jewish Commission on Law and Public Affairs as amicus curiae urging affirmance. With him on the brief were Dennis Rapps and Howard I. Rhine.
  Together with No. 75-1385, International Assn. of Machinists & Aerospace Workers, AFL-CIO, et al. v. Hardison et al., also on certiorari to the same court.
  Briefs of amici curiae urging reversal were filed by William L. Hun-gate, Edwin D. Akers, Jr., Charles A. Newman, and A. William Rolf for the Chrysler Corp.; and by Jay S. Siegel, Robert E. Williams, and Douglas S. McDowell for the Equal Employment Advisory Council.
  Briefs of amici curiae urging affirmance were filed by Acting Solicitor General Friedman, Assistant Attorney General Days, Deputy Solicitor General Wallace, Allan A. Ryan, Jr., Brian K. Landsberg, Dennis J. Dimsey, and Abner W. Sibal for the United States et al.; by Frank J. Kelley, Attorney General, Robert A. Derengoski, Solicitor General, and Michael A. Lockman and Gary G. Kress, Assistant Attorneys General, for the State of Michigan; by Beverly Gross for the New York State Division of Human Rights; by Joel M. Gora and Leo Pfeffer for the American Civil Liberties Union; by Mr. Pfeffer for the Central Conference of American Rabbis et al.; by Warren L. Johns for the General Conference of Seventh-Day Adventists; and by Ralph K. Helge for the Worldwide Church of God.
  Mr. Justice White
  delivered the opinion of the Court. Section 703 (a)(1) of the Civil Rights Act of 1964, Title VII, 78 Stat. 255, 42 U. S. C. § 2000e-2 (a)(1), makes it an unlawful employment practice for an employer to discriminate against an employee or a prospective employee on the basis of his or her religion. At the time of the events involved here, a guideline of the Equal Employment Opportunity Commission (EEOC), 29 CFR § 1605.1 (b) (1968), required, as the Act itself now does, 42 U. S. C. § 2000e (j) (1970 ed., Supp. V), that an employer, short of “undue hardship,” make “reasonable accommodations” to the religious needs of its employees. The issue in this case is the extent of the employer's obligation under Title VII to accommodate an employee whose religious beliefs prohibit him from working on Saturdays.
  I
  We summarize briefly the facts found by the District Court. 375 F. Supp. 877 (WD Mo. 1974).
  Petitioner Trans World Airlines (TWA) operates a large maintenance and overhaul base in Kansas City, Mo. On June 5, 1967, respondent Larry G. Hardison was hired by TWA to work as a clerk in the Stores Department at its Kansas City base. Because of its essential role in the Kansas City operation, the Stores Department must operate 24 hours per day, 365 days per year, and whenever an employee’s job in that department is not filled, an employee must be shifted from another department, or a supervisor must cover the job, even if the work in other areas may suffer.
  Hardison, like other employees at the Kansas City base, was subject to a seniority system contained in a collective-bargaining agreement that TWA maintains with petitioner International Association of Machinists and Aerospace Workers (IAM). The seniority system is implemented by the union steward through a system of bidding by employees for particular shift assignments as they become available. The most senior employees have first choice for job and shift assignments, and the most junior employees are required to work when the union steward is unable to find enough people willing to work at a particular time or in a particular job to fill TWA’s needs.
  In the spring of 1968 Hardison began to study the religion known as the Worldwide Church of God. One of the tenets of that religion is that one must observe the Sabbath by refraining from performing any work from sunset on Friday until sunset on Saturday. The religion also proscribes work on certain specified religious holidays.
  When Hardison informed Everett Kussman, the manager of the Stores Department, of his religious conviction regarding observance of the Sabbath, Kussman agreed that the union steward should seek a job swap for Hardison or a change of days off; that Hardison would have his religious holidays off whenever possible if Hardison agreed to work the traditional holidays when asked; and that Kussman would try to find Hardison another job that would be more compatible with his religious beliefs. The problem was temporarily solved when Hardison transferred to the 11 p. m.-7 a. m. shift. Working this shift permitted Hardison to observe his Sabbath.
  The problem soon reappeared when Hardison bid for and received a transfer from Building 1, where he had been employed, to Building 2, where he would work the day shift. The two buildings had entirely separate seniority lists; and while in Building 1 Hardison had sufficient seniority to observe the Sabbath regularly, he was second from the bottom on the Building 2 seniority list.
  In Building 2 Hardison was asked to work Saturdays when a fellow employee went on vacation. TWA agreed to permit the union to seek a change of work assignments for Hardison, but the union was not willing to violate the seniority provisions set out in the collective-bargaining contract, and Har-dison had insufficient seniority to bid for a shift having Saturdays off.
  A proposal that Hardison work only four days a week was rejected by the company. Hardison’s job was essential, and on weekends he was the only available person on his shift to perform it. To leave the position empty would have impaired supply shop functions, which were critical to airline operations; to fill Hardison’s position with a supervisor or an employee from another area would simply have undermanned another operation; and to employ someone not regularly assigned to work Saturdays would have required TWA to pay premium wages.
  When an accommodation was not reached, Hardison refused to report for work on Saturdays. A transfer to the twilight shift proved unavailing since that schedule still required Hardison to work past sundown on Fridays. After a hearing, Hardison was discharged on grounds of insubordination for refusing to work during his designated shift.
  Hardison, having first invoked the administrative remedy provided by Title VII, brought this action for injunctive relief in the United States District Court against TWA and IAM, claiming that his discharge by TWA constituted religious discrimination in violation of Title VII, 42 U. S. C. § 2000e-2 (a)(1). He also charged that the union had discriminated against him by failing to represent him adequately in his dispute with TWA and by depriving him of his right to exercise his religious beliefs. Hardison’s claim of religious discrimination rested on 1967 EEOC guidelines requiring employers “to make reasonable accommodations to the religious needs of employees” whenever such accommodation would not work an “undue hardship,” 29 CFR § 1605.1 (1968), and on similar language adopted by Congress in the 1972 amendments 'to Title VII, 42 U. S. C. § 2000e (j) (1970 ed., Supp. V).
  After a bench trial, the District Court ruled in favor of the defendants. Turning first to the claim against the union, the District Court ruled that although the 1967 EEOC guidelines were applicable to unions, the union’s duty to accommodate Hardison’s belief did not require it to ignore its seniority system as Hardison appeared to claim. As for Hardison’s claim against TWA, the District Court rejected at the outset TWA’s contention that requiring it in any way to accommodate the religious needs of its employees would constitute an unconstitutional establishment of religion. As the District Court construed the Act, however, TWA had satisfied its “reasonable accommodations” obligation, and any further accommodation would have worked an undue hardship on the company.
  The Court of Appeals for the Eighth Circuit reversed the judgment for TWA. 527 F. 2d 33 (1975). It agreed with the District Court’s constitutional ruling, but held that TWA had not satisfied its duty to accommodate. Because it did not appear that Hardison had attacked directly the judgment in favor of the union, the Court of Appeals affirmed that judgment without ruling on its substantive merits.
  In separate petitions for certiorari TWA and IAM contended that adequate steps had been taken to accommodate Hardison’s religious observances and that to construe the statute to require further efforts at accommodation would create an establishment of religion contrary to the First Amendment of the Constitution. TWA also contended that the Court of Appeals improperly ignored the District Court’s findings of fact.
  We granted both petitions for certiorari. 429 U. S. 958 (1976). Because we agree with petitioners that their conduct was not a violation of Title VII, we need not reach the other questions presented.
  II
  The Court of Appeals found that TWA had committed an unlawful employment practice under § 703 (a) (1) of the Act, 42 U. S. C. § 2000e-2 (a) (1), which provides:
  “(a) It shall be an unlawful employment practice for an employer—
  “(1) to fail or refuse to hire or to discharge any individual, or otherwise to discriminate against any individual with respect to his compensation, terms, conditions, or privileges of employment, because of such individual’s race, color, religion, sex, or national origin.”
  The emphasis of both the language and the legislative history of the statute is on eliminating discrimination in employment; similarly situated employees are not to be treated differently solely because they differ with respect to race, color, religion, sex, or national origin. This is true regardless of whether the discrimination is directed against majorities or minorities. McDonald v. Santa Fe Trail Transportation Co., 427 U. S. 273, 280 (1976). See Griggs v. Duke Power Co., 401 U. S. 424, 431 (1971).
  The prohibition against religious discrimination soon raised the question of whether it was impermissible under § 703 (a) (1) to discharge or refuse to hire a person who for religious reasons refused to work during the employer’s normal workweek. In 1966 an EEOC guideline dealing with this problem declared that an employer had an obligation under the statute “to accommodate to the reasonable religious needs of employees . . . where such accommodation can be made without serious inconvenience to the conduct of the business.” 29 CFR § 1605.1 (1967).
  In 1967 the EEOC amended its guidelines to require employers “to make reasonable accommodations to the religious needs of employees and prospective employees where such accommodations can be made without undue hardship on the conduct of the employer’s business.” 29 CFR § 1605.1 (1968). The EEOC did not suggest what sort of accommodations are “reasonable” or when hardship to an employer becomes “undue.”
  This question — the extent of the required accommodation— remained unsettled when this Court, in Dewey v. Reynolds Metals Co., 402 U. S. 689 (1971), affirmed by an equally divided Court the Sixth Circuit's decision in 429 F. 2d 324 (1970). The discharge of an employee who for religious reasons had refused to work on Sundays was there held by the Court of Appeals not to be an unlawful employment practice because the manner in which the employer allocated Sunday work assignments was discriminatory in neither its purpose nor effect; and consistent with the 1967 EEOC guidelines, the employer had made a reasonable accommodation of the employee’s beliefs by giving him the opportunity to secure a replacement for his Sunday work.
  In part “to resolve by legislation” some of the issues raised in Dewey, 118 Cong. Rec. 706 (1972) (remarks of Sen. Randolph), Congress included the following definition of religion in its 1972 amendments to Title VII:
  “The term 'religion’ includes all aspects of religious observance and practice, as well as belief, unless an employer demonstrates that he is unable to reasonably accommodate to an employee’s or prospective employee’s religious observance or practice without undue hardship on the conduct of the employer’s business.” § 701 (j), 42 U. S. C. § 2000e (j) (1970 ed., Supp. V).
  The intent and effect of this definition was to make it an unlawful employment practice under §703 (a)(1) for an employer not to make reasonable accommodations, short of undue hardship, for the religious practices of his employees and prospective employees. But like the EEOC guidelines, the statute provides no guidance for determining the degree of accommodation that is required of an employer. The brief legislative history of § 701 (j) is likewise of little assistance in this regard. The proponent of the measure, Senator Jennings Randolph, expressed his general desire “to assure that freedom from religious discrimination in the employment of workers is for all time guaranteed by law,” 118 Cong. Rec. 705 (1972), but he made no attempt to define the precise circumstances under which the “reasonable accommodation” requirement would be applied.
  In brief, the employer’s statutory obligation to make reasonable accommodation for the religious observances of its employees, short of incurring an undue hardship, is clear, but the reach of that obligation has never been spelled out by Congress or by EEOC guidelines. With this in mind, we turn to a consideration of whether TWA has met its obligation under Title VII to accommodate the religious observances of its employees.
  Ill
  The Court of Appeals held that TWA had not made reasonable efforts to accommodate Hardison’s religious needs under the 1967 EEOC guidelines in effect at the time the relevant events occurred. In its view, TWA had rejected three reasonable alternatives, any one of which would have satisfied its obligation without undue hardship. First, within the framework of the seniority system, TWA could have permitted Hardison to work a four-day week, utilizing in his place a supervisor or another worker on duty elsewhere. That this would have caused other shop functions to suffer was insufficient to amount to undue hardship in the opinion of the Court of Appeals. Second — according to the Court of Appeals, also within the bounds of the collective-bargaining contract — the company could have filled Hardison’s Saturday shift from other available personnel competent to do the job, of which the court said there were at least 200. That this would have involved premium overtime pay was not deemed an undue hardship. Third, TWA could have arranged a “swap between Hardison and another employee either for another shift or for the Sabbath days.” In response to the assertion that this would have involved a breach of the seniority provisions of the contract, the court noted that it had not been settled in the courts whether the required statutory accommodation to religious needs stopped short of transgressing seniority rules, but found it unnecessary to decide the issue because, as the Court of Appeals saw the record, TWA had not sought, and the union had therefore not declined to entertain,, a possible variance from the seniority provisions of the collective-bargaining agreement. The company had simply left the entire matter to the union steward who the Court of Appeals said “likewise did nothing.”
  We disagree with the Court of Appeals in all relevant respects. It is our view that TWA made reasonable efforts to accommodate and that each of the Court of Appeals’ suggested alternatives would have been an undue hardship within the meaning of the statute as construed by the EEOC guidelines.
  A
  It might be inferred from the Court of Appeals’ opinion and from the brief of the EEOC in this Court that TWA’s efforts to accommodate were no more than negligible. The findings of the District Court, supported by the record, are to the contrary. In summarizing its more detailed findings, the District Court observed:
  “TWA established as a matter of fact that it did take appropriate action to accommodate as required by Title VII. It held several meetings with plaintiff at which it attempted to find a solution to plaintiff’s problems. It did accommodate plaintiff’s observance of his special religious holidays. It authorized the union steward to search for someone who would swap shifts, which apparently was normal procedure.” 375 F. Supp., at 890-891.
  It is also true that TWA itself attempted without success to find Hardison another job. The District Court’s view was that TWA had done all that could reasonably be expected within the bounds of the seniority system.
  The Court of Appeals observed, however, that the possibility of a variance from the seniority system was never really posed to the union. This is contrary to the District Court’s findings and to the record. The District Court found that when TWA first-learned of Hardison’s religious observances in April 1968, it agreed to permit the union’s steward to seek a swap of shifts or days off but that “the steward reported that he was unable to work out scheduling changes and that he understood that no one was willing to swap days with plaintiff.” Id., at 888. Later, in March 1969, at a meeting held just two days before Hardison first failed to report for his Saturday shift, TWA again “offered to accommodate plaintiff’s religious observance by agreeing to any trade of shifts or change of sections that plaintiff and the union could work out .... Any shift or change was impossible within the seniority framework and the union was not willing to violate the seniority provisions set out in the contract to make a shift or change.” Id., at 889. As the record shows, Hardison himself testified that Kussman was willing, but the union was not, to work out a shift or job trade with another employee. App. 76-77.
  We shall say more about the seniority system, but at this juncture it appears to us that the system itself represented a significant accommodation to the needs, both religious and secular, of all of TWA’s employees. As will become apparent, the seniority system represents a neutral way of minimizing the number of occasions when an employee must work on a day that he would prefer to have off. Additionally, recognizing that weekend work schedules are the least popular, the company made further accommodation by reducing its work force to a bare minimum on those days.
  B
  We are also convinced, contrary to the Court of Appeals, that TWA itself cannot be faulted for having failed to work out a shift or job swap for Hardison. Both the union and TWA had agreed to the seniority system; the union was unwilling to entertain a variance over the objections of men senior to Hardison; and for TWA to have arranged unilaterally for a swap would have amounted to a breach of the collective-bargaining agreement.
  (1)
  Hardison and the EEOC insist that the statutory obligation to accommodate religious needs takes precedence over both the collective-bargaining contract and the seniority rights of TWA’s other employees. We agree that neither a collective-bargaining contract nor a seniority system may be employed to violate the statute, but we do not believe that the duty to accommodate requires TWA to take steps inconsistent with the otherwise valid agreement. Collective bargaining, aimed at effecting workable and enforceable agreements between management and labor, lies at the core of our national labor policy, and seniority provisions are universally included in these contracts. Without a clear and express indication from Congress, we cannot agree with Hardison and the EEOC that an agreed-upon seniority system must give way when necessary to accommodate religious observances. The issue is important and warrants some discussion.
  Any employer who, like TWA, conducts an around-the-clock operation is presented with the choice of allocating work schedules either in accordance with the preferences of its employees or by involuntary assignment. Insofar as the varying shift preferences of its employees complement each other, TWA could meet its manpower needs through voluntary work scheduling. In the present case, for example, Hardison’s supervisor foresaw little difficulty in giving Hardison his religious holidays off since they fell on days that most other employees preferred to work, while Hardison was willing to work on the traditional holidays that most other employees preferred to have off.
  Whenever there are not enough employees who choose to work a particular shift, however, some employees must be assigned to that shift even though it is not their first choice. Such was evidently the case with regard to Saturday work; even though TWA cut back its weekend work force to a skeleton crew, not enough employees chose those days off to staff the Stores Department through voluntary scheduling. In these circumstances, TWA and IAM agreed to give first preference to employees who had worked in a particular department the longest.
  Had TWA nevertheless circumvented the seniority system by relieving Hardison of Saturday work and ordering a senior employee to replace him, it would have denied the latter his shift preference so that Hardison could be given his. The senior employee would also have been deprived of his contractual rights under the collective-bargaining agreement.
  It was essential to TWA’s business to require Saturday and Sunday work from at least a few employees even though most employees preferred those days off. Allocating the burdens of weekend work was a matter for collective bargaining. In considering criteria to govern this allocation, TWA and the union had two alternatives: adopt a neutral system, such as seniority, a lottery, or rotating shifts; or allocate days off in accordance with the religious needs of its employees. TWA would have had to adopt the latter in order to assure Hardi-son and others like him of getting the days off necessary for strict observance of their religion, but it could have done so only at the expense of others who had strong, but perhaps nonreligious, reasons for not working on weekends. There were no volunteers to relieve Hardison on Saturdays, and to give Hardison Saturdays off, TWA would have had to deprive another employee of his shift preference at least in part because he did not adhere to a religion that observed the Saturday Sabbath.
  Title VII does not contemplate such unequal treatment. The repeated, unequivocal emphasis of both the language and the legislative history of Title VII is on eliminating discrimination in employment, and such discrimination is proscribed when it is directed against majorities as well as minorities. See supra, at 71-72. Indeed, the foundation of Hardison’s claim is that TWA and IAM engaged in religious discrimination in violation of 703 (a)(1) when they failed to arrange for him to 'have Saturdays off. It would be anomalous to conclude that by “reasonable accommodation” Congress meant that an employer must deny the shift and job preference of some employees, as well as deprive them of their contractual rights, in order to accommodate or prefer the religious needs of others, and we conclude that Title VII does not require an employer to go that far.
  (2)
  Our conclusion is supported by the fact that seniority systems are afforded special treatment under Title VII itself. Section 703 (h) provides in pertinent part:
  “Notwithstanding any other provision of this sub-chapter, it shall not be an unlawful employment practice for an employer to apply different standards of compensation, or different terms, conditions, or privileges of employment pursuant to a bona fide seniority or merit system . . . provided that such differences are not the result of an intention to discriminate because of race, color, religion, sex, or national origin . . . 42 U. S. C. § 2000e-2 (h).
  “[T]he unmistakable purpose of § 703 (h) was to make clear that the routine application of a bona fide seniority system would not be unlawful under Title VII.” Teamsters v. United States, 431 U. S. 324, 352 (1977). See also United Air Lines, Inc. v. Evans, 431 U. S. 553 (1977). Section 703 (h) is “a definitional provision; as with the other provisions of § 703, subsection (h) delineates which employment practices are illegal and thereby prohibited and which are not.” Franks v. Bowman Transportation Co., 424 U. S. 747, 758 (1976). Thus, absent a discriminatory purpose, the operation of a seniority system cannot be an unlawful employment practice even if the system has some discriminatory consequences.
  There has been no suggestion of discriminatory intent in this case. “The seniority system was not designed with the intention to discriminate against religion nor did it act to lock members of any religion into a pattern wherein their freedom to exercise their religion was limited. It was coincidental that in plaintiff’s case the seniority system acted to compound his problems in exercising his religion.” 375 F. Supp., at 883. The Court of Appeals’ conclusion that TWA was not limited by the terms of its seniority system was in substance nothing more than a ruling that operation of the seniority system was itself an unlawful employment practice even though no discriminatory purpose had been shown. That ruling is plainly inconsistent with the dictates of § 703 (h), both on its face and as interpreted in the recent decisions of this Court.
  As we have said, TWA was not required by Title VII to carve out a special exception to its seniority system in order to help Hardison to meet his religious obligations.
  c
  The Court of Appeals also suggested that TWA could have permitted Hardison to work a four-day week if necessary in order to avoid working on his Sabbath. Recognizing that this might have left TWA short-handed on the one shift each week that Hardison did not work, the court still concluded that TWA would suffer no undue hardship if it were required to replace Hardison either with supervisory personnel or with qualified personnel from other departments. Alternatively, the Court of Appeals suggested that TWA could have replaced Hardison on his Saturday shift with other available employees through the payment of premium wages. Both of these alternatives would involve costs to TWA, either in the form of lost efficiency in other jobs or higher wages.
  To require TWA to bear more than a de minimis cost in order to give Hardison Saturdays off is an undue hardship. Like abandonment of the seniority system, to require TWA to bear additional costs when no such costs are incurred to give other employees the days off that they want would involve unequal treatment of employees on the basis of their religion. By suggesting that TWA should incur certain costs in order to give Hardison Saturdays off the Court of Appeals would in effect require TWA to finance an additional Saturday off and then to choose the employee who will enjoy it on the basis of his religious beliefs. While incurring extra costs to secure a replacement for Hardison might remove the necessity of compelling another employee to work involuntarily in Hardison’s place, it would not change the fact that the privilege of having Saturdays off would be allocated according to religious beliefs.
  As we have seen, the paramount concern of Congress in enacting Title VII was the elimination of discrimination in employment. In the absence of clear statutory language or legislative history to the contrary, we will not readily construe the statute to require an employer to discriminate against some employees in order to enable others to observe their Sabbath.
  Reversed.
  The TWA-IAM agreement provides in pertinent part:
  “The principle of seniority shall apply in the application of this Agreement in all reductions or increases of force, preference of shift assignment, vacation period selection, in bidding for vacancies or new jobs, and in all promotions, demotions, or transfers involving classifications covered by this Agreement.
  “Except as hereafter provided in this paragraph, seniority shall apply in selection of shifts and days off within a classification within a department . . . .” App. 214.
  TWA is the petitioner in No. 75-1126. Petitioners in No. 75-1385 are the international, local, and district levels of IAM, hereinafter collectively referred to as IAM or the union.
  The union did have a Relief Committee organized to deal with the emergency problems of its members. The record reveals that in the past this Committee had been instrumental in arranging for temporary adjustments in work schedules to meet the needs of union members; but the record also reveals that the Relief Committee had almost never arranged permanent changes in work assignments and that Hardison never sought the assistance of that Committee.
  The District Court voiced concern that if it did not find an undue hardship in. such circumstances, accommodation of religious observances might impose “ ‘a priority of the religious over the secular’ ” and thereby raise significant questions as to the constitutional validity of the statute under the Establishment Clause of the First Amendment. 375 F. Supp. 877, 883 (WD Mo. 1974), quoting Edwards & Kaplan, Religious Discrimination and the Role of Arbitration Under Title VII, 69 Mich. L. Rev. 599, 628 (1971).
  Because the judgment in its favor was affirmed by the Court of Appeals, the union was a prevailing party below; and Hardison has not filed a petition for certiorari seeking to change that judgment. It may thus appear anomalous to have granted the union’s petition for certiorari as well as that of TWA. But the union’s view is that the judgment below against TWA seriously involves union interests, because the rationale of the Court of Appeals’ opinion, as the union understands it, “necessarily and explicitly assumes that petitioner Unions are legally obligated to waive or vary provisions of their collective bargaining agreement in order to accommodate respondent Hardison’s beliefs, if called upon by TWA to do so.” Pet. for Cert, in No. 75-1385,- p. 2. This would appear to be the position of Hardison and the EEOC in this Court. Since we reverse the judgment against TWA, we need not pursue further the union’s status in this Court.
  See McDonald v. Santa Fe Trail Transportation Co., 427 U. S. 273, 278-279 (1976); Franks v. Bowman Transportation Co., 424 U. S. 747, 763 (1976); McDonnell Douglas Corp. v. Green, 411 U. S. 792, 800 (1973); Griggs v. Duke Power Co., 401 U. S. 424, 429-430 (1971).
  From the outset, Congress has said that “[t]he purpose of [Title VII] is to eliminate, through' the utilization of formal and informal remedial procedures, discrimination in employment based on race, color, religion, or national origin.” H. R. Rep. No. 914, 88th Cong., 1st Sess., 26 (1963). See 110 Cong. Rec. 13079-13080 (1964) (remarks of Sen. Clark). When Congress amended Title VII in 1972, it did not waver from its principal goal. While Congressmen differed on the best methods to eliminate discrimination in employment, no one questioned the desirability of seeking that goal. Compare H. R. Rep. No. 92-238 (1971) (majority report of the Committee of the Whole House), with id,., at 68 (minority report).
  The EEOC expressed the view that “undue hardship, for example, may exist where the employee’s needed work cannot be performed by another employee of substantially similiar qualifications during the period of absence of the Sabbath observer,” 29 CFR § 1605.1 (1968). This single example was by no means intended to be exhaustive. In substance, the EEOC left further definition of its guidelines to its review of “each case on an individual basis in an effort to seek an equitable application of these guidelines to the variety of situations which arise due to the varied religious practices of the American people.” Ibid. The EEOC at that time did not purport to change the view expressed in its 1966 guidelines that work schedules generally applicable to all employees may not be unreasonable, even if they do not “operate with uniformity . . . upon the religious observances of [all] employees.” The EEOC’s present view, expressed in an amicus curiae brief filed in support of Hardison and the Court of Appeals’ judgment, is now otherwise, at least to some extent.
  Judgment entered by an equally divided Court is not “entitled to precedential weight,” Neil v. Biggers, 409 U. S. 188, 192 (1972). Our ruling in Dewey thus does not resolve the questions there presented. Other factors, as well, make the impact of Dewey inconclusive. The conduct alleged to be an unlawful employment practice occurred prior to the promulgation of the 1967 guidelines, and the Court of Appeals expressed the view that those guidelines should not be given retroactive effect. Also, an earlier ruling by an arbitrator was held to have conclusively resolved the religious discrimination question in favor of the employer. But see Alexander v. Gardner-Denver Co., 415 U. S. 36 (1974). Finally, the employer in Dewey was not excused from a duty to accommodate; the Court of Appeals simply held that the employer had satisfied any obligation that it might have had under the statute.
  Section 701 (j) was added to the 1972 amendments on the floor of the Senate. The legislative history of the measure consists chiefly of a brief floor debate in the Senate, contained, in less than two pages of the Congressional Record and consisting principally of the views of the proponent of the measure, Senator Jennings Randolph. 118 Cong. Rec. 705-706 (1972).
  The Congressional Record, 118 Cong. Rec. 706-713 (1972), also contains reprints of Dewey and Riley v. Bendix Corp., 330 F. Supp. 583 (MD Fla. 1971), rev’d, 464 F. 2d 1113 (CA5 1972), as well as a brief synopsis of the new provision, which makes reference to Dewey, 118 Cong. Rec. 7167 (1972). The significance of the legislative references to prior case law is unclear. In Riley the District Court ruled that an employer who discharged an employee for refusing to work on his Sabbath had not committed an unfair labor practice even though the employer had not made any effort whatsoever to accommodate the employee’s religious needs. It is clear from the language of § 701 (j) that Congress intended to change this result by requiring some form of accommodation; but this tells us nothing about how much an employer must do to satisfy its statutory obligation.
  The reference to Dewey is even more opaque:
  “The purpose of this subsection is to provide the statutory basis for EEOC to formulate guidelines on discrimination because of religion such as those challenged in Dewey v. Reynolds Metals Company, 429 F. 2d 325 (6th Cir. 1970), Affirmed by an equally divided court, 402 U. S. 689 (1971).” 118 Cong. Rec. 7167 (1972). Clearly, any suggestion in Dewey that an employer may not be required to make reasonable accommodation for the religious needs of its employees was disapproved by § 701 (j); but Congress did not indicate that “reasonable accommodation” requires an employer to do more than was done in Dewey, apparently preferring to leave that question open for future resolution by the EEOC. See also n. 8, supra.
  Cases decided by the Courts of Appeals since the enactment of the 1972 amendments to Title VII similarly provide us with little guidance as to the scope of the employer’s obligation. In circumstances where an employer has declined to take steps that would burden some employees in order to permit another employee or prospective employee to observe his Sabbath, the Fifth, Sixth, and Tenth Circuits have found no violation for failure to accommodate. Williams v. Southern Union Gas Co., 529 F. 2d 483 (CA10 1976); Reid v. Memphis Publishing Co., 521 F. 2d 512 (CA6 1975), cert. denied, 429 U. S. 964 (1976), pet. for rehearing pending, No. 75-1105; Johnson v. U. S. Postal Service, 497 F. 2d 128 (CA5 1974). But the Fifth and Sixth Circuits have also reached the opposite conclusion on similar facts. Draper v. United States Pipe & Foundry Co., 527 F. 2d 515 (CA6 1975); Cummins v. Parker Seal Co., 516 F. 2d 544 (CA6 1975), aff’d by equally divided Court, 429 U. S. 65 (1976); Riley v. Bendix Corp., 464 F. 2d 1113 (CA5 1972). These apparent intra-Circuit conflicts may be explainable on the basis of the differing facts of each case, but neither the Fifth nor the Sixth Circuit has suggested a theory of decision to justify the differing results that have been reached.
  Ordinarily, an EEOC guideline is not entitled to great weight where, as here, it varies from prior EEOC policy and no new legislative history has been introduced in support of the change. General Electric Co. v. Gilbert, 429 U. S. 125, 140-145 (1976). But where “Congress has not just kept its silence by refusing to overturn the administrative construction, but has ratified it with positive legislation,” Red Lion Broadcasting Co. v. FCC, 395 U. S. 367, 381-382 (1969) (footnote omitted), the guideline is entitled to some deference, at least sufficient in this case to warrant our accepting the guideline as a defensible construction of the pre-1972 statute, i. e., as -imposing on TWA the duty of “reasonable accommodation” in the absence of “undue hardship.” We thus need not consider whether § 701 (j) must be applied retroactively to the facts of this litigation.
  “This Court has long held that employee expectations arising from a seniority system agreement may be modified by statutes furthering a strong public policy interest.” Franks v. Bowman Transportation Co., 424 U. S., at 778. Cf. Alexander v. Gardner-Denver Co., 415 U. S. 36 (1974). In Franks we held that it was permissible to award retroactive seniority to victims of past discrimination in order to implement the strong congressional policy of making victims of discrimination whole. Franks is not dispositive of the present case since here there is no evidence of past discrimination that must be remedied. Not only is the “make-whole” policy not present in this case, but, as we shall see, the strong congressional policy against discrimination in employment argues against interpreting the statute to require the abrogation of the seniority rights of some employees in order to accommodate the religious needs of others.
  Franks v. Bowman Transportation Co., is not to the contrary. In Franks we held that “once an illegal discriminatory practice occurring after the effective date of the Act is proved,” 424 U. S., at 762, § 703 (h) does not bar an award of retroactive seniority status to victims of that discriminatory practice. Here the suggested exception to the TWA-IAM seniority system would not be remedial; the operation of the seniority system itself is said to violate Title VII. In such circumstances, § 703 (h) unequivocally mandates that there is no statutory violation in the absence of a showing of discriminatory purpose. See United Air Lines, Inc. v. Evans, 431 U. S. 553, 558-560 (1977).
  Despite its hyperbole and rhetoric, the dissent appears to agree with — at least it stops short of challenging — the fundamental proposition that Title VII does not require an employer and a union who have agreed on a seniority system to deprive senior employees of their seniority rights in order to accommodate a junior employee’s religious practices. This is the principal issue on which TWA and the union came to this Court. The dissent is thus reduced to (1) asserting that the statute requires TWA to accommodate Hardison even though substantial expenditures are required to do so; and (2) advancing its own view of the record to show that TWA could have done more than it did to accommodate Hardison without violating the seniority system or incurring substantial additional costs. We reject the former assertion as an erroneous construction of the statute. As for the latter, we prefer the findings of the District Judge who heard the evidence. Thus, the dissent suggests that through further efforts TWA or the union might have arranged a temporary or permanent job swap within the seniority system, despite the District Court’s express finding, supported by the record, that “[t]he seniority provisions . . . precluded the possibility of plaintiff’s changing his shift.” 375 F. Supp., at 884. Similarly, the dissent offers two alternatives — sending Hardison back to Building 1 or allowing him to work extra days without overtime pay— that it says could have been pursued by TWA or the union, even though neither of the courts below even hinted that these suggested alternatives would have been feasible under the circumstances. Furthermore, Buildings 1 and 2 had separate seniority lists, and insofar as the record shows, a return to Building 1 would not have solved Hardison’s problems. Hardison himself testified that he “gave up” his Building 1 seniority when he came to Building 2, App. 104, and that the union would not accept his early return to Building 1 in part “because the problem of seniority came up again.” Id., at 71. We accept the District Court’s findings that TWA had done all that it could do to accommodate Hardison’s religious beliefs without either incurring substantial costs or violating the seniority rights of other employees. See 375 F. Supp., at 891.
  The dissent argues that “the costs to TWA of either paying overtime or not replacing respondent would [not] have been more than de minimis." Post, at 92 n. 6. This ignores, however, the express finding of the District Court that “[b]oth of these solutions would have created an undue burden on the conduct of TWA’s business,” 375 F. Supp., at 891, and it fails to take account of the likelihood that a company as large as TWA may have many employees whose religious observances, like Hardi-son’s, prohibit them from working on Saturdays or Sundays.
choices: stay, petition, or motion granted affirmed reversed reversed and remanded vacated and remanded affirmed and reversed (or vacated) in part affirmed and reversed (or vacated) in part and remanded vacated petition denied or appeal dismissed modify remand unusual disposition