with whom Mr. Justice Brennan and Mr. Justice Blackmun join, dissenting.
In the California brewing industry, an employee’s rights and benefits are largely dependent on whether he is a “permanent” employee within the meaning of the collective-bargaining agreement. Permanent employees are laid off after all other employees. If laid off at one facility, a permanent employee is permitted to replace the least senior nonperma-nent employee at any other covered facility within the local area. Permanent employees are selected before temporary employees to fill vacancies. They have exclusive rights to supplemental unemployment benefits upon layoff and receive higher wages and vacation pay for the same work performed by other employees. Permanent employees have first choice of vacation times, less rigorous requirements for qualifying for holiday pay, exclusive access to veterans’ reinstatement and seniority rights, and priority in assignment of overtime work among bottlers.
According to respondent Bryant’s complaint, no Negro has ever attained permanent employee status in the California brewing industry.1
*612The provision of the collective-bargaining agreement at issue here defines a permanent employee as one “who . . . has completed forty-five weeks of employment ... in one classification in one calendar year as an employee of the brewing industry in this State.” An employee who works 44 weeks per year for his entire working life remains a temporary employee. By contrast, an employee who works 45 weeks in his first year in the industry attains permanent employee status. This simple fact belies the Court’s conclusion that the 45-week requirement “does not depart significantly from commonly accepted concepts of ‘seniority.’ ” Ante, at 609. Since I am unable to agree that the provision at issue is part of a “seniority system” under § 703 (h) of Title VII, I dissent.
I
Neither Title VII nor its legislative history provides a comprehensive definition of the term “seniority system.”2 The Court is therefore correct in concluding that the term must be defined by reference to “commonly accepted notions about ‘seniority’ in industrial relations” and “in the context of Title VII and this country’s labor policy.” Ante, at 605. Those “commonly accepted notions,” however, do not lead to the Court’s holding today. And I believe that the relevant policies do not support that holding, but instead require that it be rejected.
The concept of “seniority” is not a complicated one. The fundamental principle, as the Court recognizes, ante, at 606, is that employee rights and benefits increase with length of service. This principle is reflected in the very definition of the term, as found in dictionaries'3 and treatises and articles in *613the field of industrial relations.4 To quote from a few of the sources on which the Court purports to rely today: “Seniority is a system of employment preference based on length of serv*614ice; employees with the longest service are given the greatest job security and the best opportunities for advancement.” Aaron, Reflections on the Legal Nature and Enforceability of Seniority Rights, 75 Harv. L. Rev. 1532, 1534 (1962). "The variations and combinations of seniority principles are very great, but in all cases the basic measure is length of service, with preference accorded to the senior worker.” Cooper & Sobol, Seniority and Testing under Fair Employment Laws: A General Approach to Objective Criteria of Hiring and Promotion, 82 Harv. L. Rev. 1598, 1602 (1969). “Seniority grants certain preferential treatment to long-service employees almost at the expense of short-service employees. . . . [Sjeniority is defined as length of service.” E. Beal, E. Wickersham, & P. Kienast, The Practice of Collective Bargaining 430 (1972).
It is hardly surprising that seniority has uniformly been defined in terms of cumulative length of service. No other definition could accord with the policies underlying the recognition of seniority rights. A seniority system provides an objective standard by which to ascertain employee rights and protections, thus reducing the likelihood of arbitrariness or caprice in employer decisions. At the same time, it promotes stability and certainty among employees, furnishing a predictable method' by which to measure future employment position. See, e. g., Sayles, Seniority: An Internal Union Problem, 30 Harv. Bus. Rev. 55 (1952); C. Golden & H. Ruttenberg, The Dynamics of Industrial Democracy 128-131 (1973); Cooper & Sobol, supra, at 1604^1605.
The Court concedes this general point, recognizing that a “ 'seniority system’ is a scheme that, alone or in tandem with non-'seniority’ criteria, allots to employees ever improving employment rights and benefits as their relative lengths of pertinent employment increase.” Ante, at 605-606 (footnote omitted). In my view, that concession is dispositive of this case. The principal effect of the 45-week requirement is to ensure that employee rights and benefits in the California *615brewing industry are not “ever improving” as length of service increases. Indeed, cumulative length of service is only incidentally relevant to the 45-week rule. The likelihood that a temporary employee will attain permanent employee status is largely unpredictable. The 45-week period, which is exclusive of vacation, leaves of absence, and time lost because of injury or sickness, represents almost 90% of the calendar year. Even if an employee is relatively senior among temporaries, his ability to work 45 weeks in a year will rest in large part on fortuities over which he has no control. The most obvious reason that employees have been prevented from attaining permanent employee status — a reason barely referred to by the Court — is that the brewing industry is a seasonal one. An employee may also be prevented from becoming permanent because of replacement by permanent employees or an employer’s unexpected decision to lay off a particular number of employees during the course of a year.5 It is no wonder that the accrual of seniority by temporary employees has not led with any regularity to the acquisition of permanent employee status.6 In sum, the 45-week rule does not have *616the feature of providing employees with a reasonably certain route by which to measure future employment position. So understood, the 45-week rule has very little to do with seniority, for it makes permanent status turn on fortuities over which the employee has no control, not on length of service with the employer or in the relevant unit.
The Court avoids this conclusion by little more than assertion. It observes that the 45-week rule acts as a threshold requirement for entry onto the seniority track composed of permanent employees, but eliminates the force of that observation with the inevitable concession that such threshold requirements are not necessarily entitled to § 703 (h) exemption.7 It notes that the 45-week requirement “focuses on length of employment,” and proceeds to the unexplained conclusion that it therefore “does not depart significantly from commonly accepted concepts of 'seniority.’ ” And it adds that more senior temporary employees tend to have a greater opportunity to obtain work and thus to attain permanent status through 45 weeks of employment in a calendar year.
The Court’s analysis, of course, is largely dependent on its conclusion that since the 45-week requirement is one measured by time of service, it does not depart from common concepts of seniority. That conclusion, however, is foreclosed by the Court’s own definition of a seniority system as one in which employee rights increase with cumulative length of *617service — not length of service within a calendar year. The mere fact that the 45-week rule is in some sense a measure of “time” does not demonstrate a valid relation to concepts of seniority. Such a conclusion would make the § 703 (h) exemption applicable to a rule under which permanent employee status is dependent on number of days served within a week, or hours served within a day.8
Nor is there much force to the suggestion that the 45-week requirement somehow becomes part of a seniority system because permanent employee status is more easily achieved by the more senior temporary employees. I could agree with the Court's decision if petitioners demonstrated that the collective-bargaining agreement actually operates to reward employees in order of cumulative length of service. But at this stage of the litigation there is no evidence that temporary employees attain permanent status in a way correlating even roughly with total length of employment. The mere possibility that senior temporary employees are more likely to work for 45 weeks is, in my view, insufficient.9 It might as well be said that a law conditioning permanent employee status on the attainment of a certain level of skill is a “seniority” provision since skills tend to increase with length of service. A temporary employee is always subject to a risk that for some reason *618beyond his control, he will be unable to work the full 45 weeks and be forced to start over again.
II
Since the 45-week rule operates as a threshold requirement with no relation to principles of seniority, I believe that the rule is for analytical purposes no different from an educational standard or physical test which, as the Court indicates, is plainly not entitled to § 703 (h) exemption. Accordingly, I think it clear that the 45-week requirement is not part of a “seniority system” within the meaning of § 703 (h). But if the question were perceived to be close, I would be guided by the familiar principle that exemptions to remedial statutes should be construed narrowly. “To extend an exemption to other than those plainly and unmistakably within its terms and spirit is to abuse the interpretative process and to frustrate the announced will of the people.” Phillips Co. v. Walling, 324 U. S. 490, 493 (1945). See, e. g., Group Life & Health Ins. Co. v. Royal Drug Co., 440 U. S. 205, 231 (1979); Abbott Laboratories v. Portland Retail Druggists Assn., 425 U. S. 1, 12 (1976); Peyton v. Rowe, 391 U. S. 54, 65 (1968). The effect of § 703 (h) is to exempt seniority systems from the general prohibition on practices which perpetuate the effects of racial discrimination. This exception is a limited one in derogation of the overarching purpose of Title VII, “the integration of blacks into the mainstream of American society,” Steelworkers v. Weber, 443 U. S. 193, 202 (1979). A statute designed to remedy the national disgrace of discrimination in employment should be interpreted generously to comport with its primary purpose; exemptions should be construed narrowly so as not to undermine the effect of the general prohibition. Today the Court not only refuses to apply this familiar principle of statutory construction, it does not even acknowledge it.
*619In my view, the Court’s holding is fundamentally at odds with the purposes of Title VII and the basic function of the § 703 (h) exemption. I dissent.10
In the present procedural posture of the case, of course, the allegations of the complaint must be accepted as true.
The legislative history does, however, provide a bit more guidance than the Court admits. The fact that the sole example of a seniority system given in the congressional debates is one in which rights increase with cumulative length of service is at least suggestive. See ante, at 605, n. 10.
See, e. g., Webster’s Third New International Dictionary 2066 (unabridged ed. 1961) (“a status attained by length of continuous service *613ías in a company . . .) to which are attached by custom or prior collective agreement various rights or privileges”); Random House Dictionary of the English Language 1299 (1966) (“priority, precedence, or status obtained as the result of a person’s length of service”); Black’s Law Dictionary 1222 (5th ed. 1979) (“As used with reference to job seniority, worker with most years of service is first promoted within range of jobs subject to seniority, and is the last laid off, proceeding so on down the line to the youngest in point of service”); Ballentine’s Law Dictionary 1160 (1969) (“the principle in labor relations that length of employment determines the order of layoffs, rehirings, and advancements”).
See, e. g., Roberts’ Dictionary of Industrial Relations 390 (1966) (“The length of service an individual employee has in the plant. . . . The seniority principle rests on the assumption that the individuals with the greatest length of service within the company should be given preference in employment”); United States Department of Labor, Bureau of Labor Statistics, Bulletin No. 908-11, p. 1 (1949) (“A seniority program aims to provide maximum security in employment to those with the longest service”); E. Dangel & I. Shriber, The Law of Labor Unions § 15 (1941) (“Seniority ... is an employment advantage in the matter of the choice of and the right to work in one’s occupation on the basis of an employee’s length of service”); BNA, Collective Bargaining Contracts, Techniques of Negotiation and Administration with Topical Classification of Clauses 488 (1941) (“The term [seniority] refers to length of service with the employer or in some division of an enterprise”); Meyers, The Analytic Meaning of Seniority, Industrial Relations Research Association, Proceedings of Eighteenth Annual Meeting 194 (1966) (“Seniority is the application of the criterion of length of service for the calculation of relative equities among employees”); McCaffrey, Development and Administration of Seniority Provisions, Proceedings of New York University Second Annual Conference on Labor 132 (1949) (“seniority may be defined as the length of company-recognized service as applied to certain employer-employee relationships”) ; Christenson, Seniority Rights Under Labor Union Working Agreements, 11 Temp. L. Q. 355 (1937) (“seniority is a rule providing that employers promote, lay-off and re-employ labor, according to length of previous service”). Cf. P. Selznick, Law, Society, and Industrial Justice 203 (1969) (referring to the “ 'rather general feeling that a worker who has spent many years on his job has some stake in that job and in the business of which it is a part’ ”).
Indeed, the agreement expressly provides that a permanent employee laid off at one facility will replace (or “bump”) the temporary employee with the lowest plant seniority, even if that employee has more industry seniority than others. As a result, temporaries who are relatively senior in terms of industry seniority may have less opportunity to work 45 weeks in a calendar year than temporaries with less industry seniority but more plant seniority. Thus, it is simply not true that temporary employees obtain permanent employee status in order of cumulative length of employment, for the requisite 45 weeks is computed on the basis of service in the industry rather than in particular plants.
The Court acknowledges this point, ante, at 610, n. 22, but responds that a system which would fall within § 703 (h) in an expanding labor market does not lose that status by virtue of the fact that the labor market is contracting. In the Court’s words, however, the question is whether the 45-week rule is a part of a seniority system because it “allots to employees ever improving employment rights and benefits as their relative lengths of pertinent employment increase.” In that context it is *616surely relevant whether the 45-week provision does in fact operate to reward cumulative length of service, or serves instead as a virtually impassable barrier to advancement.
As the Court’s own analysis suggests, the 45-week provision is entirely different from the seniority provisions involved in Teamsters v. United States, 431 U. S. 324 (1977). At issue in that case was a seniority system granting some benefits on the basis of an employee’s cumulative length of service with the company, and others on the basis of cumulative length of service in a particular job category. In both cases employee rights and benefits depended on total length of service in the relevant unit, not on the length of service within a calendar year.
For example, there can be no serious question that a provision making permanent status dependent on 7 days of work per week, or 12 hours per day, would not be part of a “seniority system” within the meaning of §703 (h).
I could understand, although I do not favor, a decision remanding this case for factual findings on the question whether temporary employees in fact acquire permanent status and, if so, whether they do so in order of cumulative length of service. In my view, it is extraordinary for the Court to conclude, in a factual vacuum and on the authority of nothing other than petitioners' word, that “the rule does not distort the operation of the basic system established by the Agreement, which rewards employment longevity with heightened benefits.” See also n. 5, supra.
To decide this case we are not required to offer a complete definition of the term “seniority system” within the meaning of § 703 (h). Nor are we called upon to canvass and evaluate rules “ancillary” to seniority systems. The question whether all of the rules listed by the Court, ante, at 607, nn. 17-20, are part of a seniority system is not at all easy, and the Court’s own reasoning demonstrates that its discussion of those rules is gratuitous and does little to advance analysis of the 45-week requirement. That requirement serves none of the functions of an “ancillary” rule.