delivered the opinion of the Court.

The issue presented is whether Congress violates the equal protection component of the Fifth Amendment’s Due Process Clause1 by requiring retirement at age 60 of federal employees *95covered by the Foreign Service retirement and disability system but not those covered by the Civil Service retirement and disability system. A three-judge District Court was convened to hear this challenge to the constitutionality of a federal statute by appellees, a group of former and present participants in the Foreign Service retirement system. Treating the case as submitted on cross motions for summary judgment, the District Court examined the affidavits and allegations presented by both sides, held the distinction invalid, and gave judgment for appellees. 436 F. Supp. 134 (DC 1977).2 We noted probable jurisdiction, 436 U. S. 903 (1978), and now reverse.

I

The statutory provision under attack, § 632 of the Foreign Service Act of 1946, 60 Stat. 1015, as amended, 22 U. S. C. § 1002, mandates the retirement at age 60 of participants in the Foreign Service retirement system.3 That system orig*96inally covered only Foreign Service officers in the State Department, but it has been expanded to include Foreign Service Reserve officers with unlimited tenure,4 career Foreign Service Staff officers and employees,5 Foreign Service Information officers and career staff in the International Communication Agency,6 and certain employees of the Agency for International Development.7 Unlike these employees, personnel covered by the Civil Service retirement system presently face no mandatory retirement age8 and, when this suit was brought, were not required to retire until age 70.'9

Appellees have not suggested that the statutory distinction between Foreign Service personnel over age 60 and other federal employees over that age10 burdens a suspect group or *97a fundamental interest; and in cases where these considerations are absent, courts are quite reluctant to overturn governmental action on the ground that it denies equal protection of the laws.11 The Constitution presumes that, absent some reason to infer antipathy, even improvident decisions will eventually be rectified by the democratic process12 and that judicial intervention is generally unwarranted no matter how unwisely we may think a political branch has acted. Thus, we will not overturn such a statute unless the varying treatment of different groups or persons is so unrelated to the achievement of any combination of legitimate purposes that we can only conclude that the legislature’s actions were irrational. The District Court and the parties are in agreement that whether § 632 violates equal protection should be determined under the standard stated in Massachusetts Board of Retirement v. Murgia, 427 U. S. 307 (1976), and similar cases; and thus that the section is valid if it is “rationally related to furthering a legitimate state interest.” Id., at 312.

In arguing that § 632 easily satisfies this standard, the appellants submit that one of their legitimate and substantial goals is to recruit and train and to assure the professional competence, as well as the mental and physical reliability, of the corps of public servants who hold positions critical to our foreign relations, who more often than not serve overseas, frequently under difficult and demanding conditions, and who must be ready for such assignments at any time. Neither the District Court nor appellees dispute the validity of this goal. *98The appellants also submit that compulsory retirement at age 60 furthers this end in two principal ways: first, as an integral part of the personnel policies of the Service designed to create predictable promotion opportunities and thus spur morale and stimulate superior performance in the ranks; second, by removing from the Service those who are sufficiently old that they may be less equipped or less ready than younger persons to face the rigors of overseas duty in the Foreign Service. The District Court rejected each of these latter submissions and in our view erred in each instance.

II

At least since the enactment of the Rogers Act in 1924, which created the Foreign Service by reorganizing the diplomatic and consular services into a single entity, Congress has recognized the distinctive requirements associated with the conduct of the country’s foreign relations and has provided personnel policies for the Foreign Service separate and apart from the general Civil Service system. Among other differences, Foreign Service officers have been subject to an earlier retirement age than is true in the Civil Service.

Congress continued to give special attention to the Foreign Service when it passed the Foreign Service Act of 1946, 60 Stat. 999, which, with amendments, is still in effect. That Act reorganized the Foreign Service, provided it with a new personnel structure, and revised its retirement system. The intention was to produce a “disciplined and mobile corps of trained men . . . through entry at the bottom on the basis of competitive examination and advancement by merit to positions of command.” H. R. Rep. No. 2508, 79th Cong., 2d Sess., 1 (1946).13 In furtherance of “the fundamental career *99principle” 14 that had earlier been established for the Service, id., at 5, Congress found that “ft] he promotion system must insure the rapid advancement of men of ability to positions of responsibility and the elimination of men who have reached their ceilings of performance.” Id., at 2-3. Thus, not only was initial selection to be on the basis of merit but Foreign Service officers were also to be classified based on their individual abilities and to be regularly examined for promotion by selection boards. Those officers failing to measure up to the performance expected for their class or who had failed to win promotion within an allotted time were “selected out.” The aim was to stimulate superior performance and to retain only those capable of conducting themselves in this manner in widely different assignments around the world.

It was also in 1946 that the compulsory retirement age for most classes of Foreign Service officers was lowered from 65 to 60. This provision, § 632, was grouped with the selection-out sections of the Act.15 Together these sections “prescribe the *100criteria as to length of service in classes which will determine whether officers are selected out or retired,” H. R. Rep. No. 2508, supra, at 90, and were designed “to assure a reasonable pyramid of promotion.” Ibid. The retirement and selection-out provisions are part of an integral plan to create “a correctly balanced Service that [was] constructed so that the size of the various classes would correspond with the distribution of the work load of the Service.” Ibid. Selection out operates primarily at the lower levels of the Service; compulsory retirement operates at the top of the pyramid. Congress in 1946 required officers in the then-highest category,16 career ministers, and in the next-highest, class 1, to retire at ages 65 and 60, respectively. These officers were not subject to selection out by the 1946 Act,17 but as Congress expressly noted with respect to class 1, “the mandatory provisions of the retirement for age . . . accomplish the desired result of insuring turn-over in this class.” Id., at 91.18

The District Court nevertheless rejected this justification for § 632, stating in conclusory fashion that “recruiting and promoting younger people solely because of their youth is inherently discriminatory and cannot provide a legitimate basis for the statutory scheme.” 436 F. Supp., at 136. Whether or not this is a sound legal proposition, we think that the *101District Court mischaracterized the purpose of § 632 and the manner in which it operates. Congress was intent not on rewarding youth qua youth, but on stimulating the highest performance in the ranks of the .Foreign Service by assuring that opportunities for promotion would be available despite limits on the number of personnel classes and on the number of positions in the Service. Aiming at superior achievement can hardly be characterized as illegitimate, and it is equally untenable to suggest that providing promotion opportunities through the selection-out process and through early retirement does not play an acceptable role in the process. As this Court has previously observed with respect to the selection-out structure provided by Congress for naval officers, which was the model for the Foreign Service Act of 1946, the scheme “results in a flow of promotions commensurate with the Navy’s current needs and serves to motivate qualified commissioned officers to so conduct themselves that they may realistically look forward to higher levels of command.” Schlesinger v. Ballard, 419 U. S. 498, 510 (1975).

The District Court also rejected this justification for § 632 because “there is no obvious reason why [it] would not equally apply to the Civil Service.” 436 F. Supp., at 136. But this criticism ignores the evident congressional conviction that the country should be at great pains to assure the high quality of those occupying positions critical to the conduct of our foreign relations in the post-war world.19 Congress plainly intended *102to create a relatively small, homogeneous, and particularly able corps of Foreign Service officers. It was thought that the tasks performed by this corps were sufficiently demanding and important to the Nation that it was necessary to pursue more rigorous policies to ensure excellence than those generally applicable in the Government. There is no selection-out system in the Civil Service, for example; the competitive examination process is not generally as rigorous; and there are far wider variations in the nature of the various Civil Service positions and personnel. Perhaps Congress will someday attempt to devise a regime such as this one for all federal employees, but for now it has determined to employ it only in connection with what it deems to be a few distinctive groups such as the Foreign Service. See also Civil Service Reform Act of 1978, Pub. L. 95-454, §§ 3 (6), 401-415, 92 Stat. 1113, 1154-1179 (creating Senior Executive Service). The judgment that the Foreign Service needs such a system more than do many other departments is one of policy, and this kind of policy, under our constitutional system, ordinarily is to be “fixed only by the people acting through their elected representatives.” Firemen v. Chicago, R. I. & P. R. Co., 393 U. S. 129, 138 (1968). Since the congressional judgment to place a high value on the proper conduct of our foreign affairs can hardly be said to be constitutionally impermissible, it was not for the District Court to refuse to accept it.20

*103III

The appellants also submit that the Foreign Service involves extended overseas duty under difficult and often hazardous conditions and that the wear and tear on members of this corps is such that there comes a time when these posts should be filled by younger persons. Mandatory retirement, it is said, minimizes the risk of less than superior performance *104by reason, of poor health or loss of vitality. In this respect, the appellants accurately reflect the legislative record, which without doubt articulates both the purpose of maintaining a competent Foreign Service and the relationship of required retirement to that goal.

As we have indicated, under the Rogers Act retirement of Foreign Service officers was required at 65, whereas under the relevant statute the retirement age for most Civil Service employees with sufficient length of service was 70 years of age. Choosing the lower age for the Foreign Service was a considered choice.21 The principal sponsor of the legislation identified the reason for retiring Foreign Service and military officers earlier than Civil Service employees:

“I think the analogy of the foreign service officer to the Army officer and to the naval officer is much more complete than to the civil-service employee in Washington.

“The foreign-service officer is going hither and yon about the world, giving up fixed places of abode, often rendering difficult and hazardous service of prime importance to the United States.

“I call to the attention of the gentleman the fact that the kind of service which these men must render involves going to the Tropics; it involves very difficult and unsettling changes in the mode of life. The consensus of opinion was that the country was better off to retire them, as a general rule, at 65.” 65 Cong. Rec. 7564-7565 (1924) (Rep. Rogers).

In the intervening years, the Federal Government has often repeated the concern first raised in 1924.22 Congress not only *105retained the lower retirement age for Foreign Service officers when it reorganized the Foreign Service in 1946, but it also lowered the age to 60. In expanding the coverage of the Foreign Service retirement system to reach others than Foreign Service officers, Congress obviously reaffirmed its own judgment that the system should provide a lower retirement age than in the Civil Service system, just as it did in 1978 when it repealed the mandatory age for the retirement of Civil Service employees but left intact the rule for those under the Foreign Service system.23

The District Court did not deny the legitimacy of the *106legislative purpose to assure a vigorous and competent Foreign Service, nor did it reject the proposition that the mandatory-retirement provision could rationally be deemed to serve that end. It thus assumed that overseas duty is more demanding than stateside duty and that those over age 60 often axe less able to face the rigors of the Foreign Service. The District Court nevertheless invalidated § 632 because it was deemed to discriminate against older Foreign Service employees vis-a-vis those older employees in the Civil Service who serve overseas in comparable positions for nearly as long as do Foreign Service personnel and yet are not forced to retire at age 60. Only a small percentage of all United States civilians working in foreign countries for this Government are within the scope of § 632, and, according to the District Court, it is “patently arbitrary and irrational” to impose the disadvantage of early retirement upon only those relatively few. 436 F. Supp., at 138.

Our first difficulty with this conclusion is that it ignores what we have already pointed out — namely, that Congress has legislated separately for the Foreign Service and has gone to great lengths to assure that those conducting our foreign relations will be sufficiently competent and reliable in all respects. If Congress attached special importance to high performance in these positions, which it seems to us that it did, it was quite rational to avoid the risks connected with having older employees in the Foreign Service but to tolerate those risks in the Civil Service. Whether or not individual judges may agree with this assessment, it is not for the courts to reject it.

Putting aside this rational basis for sustaining § 632, however, the District Court was in error for other reasons in invalidating the statute on the ground that Civil Service employees serving overseas under similar conditions and facing comparable hardships were not also subject to the burden of early retirement. Those subject to § 632 compose a rela*107tively small group of public servants furnishing the required professionalism in the Foreign Service. Approximately 60% of them are serving in overseas posts at any one time. Almost all of them are subject to assignment to such posts at any time as a condition of their employment.24 Each such person is assigned and reassigned with some regularity and each spends a substantial portion of his career overseas. Even accepting the District Court’s judgment that some Civil Service employees serve in foreign posts under conditions as trying as those faced by Foreign Service officers, the latter are trained for and experienced at performing tasks in the Foreign Service; they are not freely interchangeable with Civil Service employees. It would thus appear sensible that the Government would take steps to assure itself that not just some, but all, members of the Service have the capability of rendering superior performance and satisfying all of the conditions of the Service.

The same is not true of the Civil Service. Only approximately 5% of these employees serve overseas at any one time, and foreign duty is in the main a voluntary matter.25 We *108are unwilling to hold that if Congress deems early retirement a useful device to maintain the quality of the Foreign Service it may nevertheless not adopt it without insisting on the same retirement age for all Civil Service employees or at least for those Civil Service employees who choose to seek a career in overseas service. In order to staff the overseas Civil Service positions with sufficiently competent persons Congress obviously has not thought it useful to provide for retirement at age 60. At least to date, its judgment has been otherwise with respect to the Foreign Service, and that judgment is not invalid as a denial of equal protection.

Even if the classification involved here is to some extent both underinclusive and overinclusive, and hence the line drawn by Congress imperfect, it is nevertheless the rule that in a case like this “perfection is by no means required.” Phillips Chemical Co. v. Dumas School Dist., 361 U. S. 376, 385 (1960); accord, San Antonio School Dist. v. Rodriguez, 411 U. S. 1, 51 (1973). The provision “does not offend the Constitution simply because the classification 'is not made with mathematical nicety ....’” Dandridge v. Williams, 397 U. S. 471, 485 (1970), quoting Lindsley v. Natural Carbonic Gas Co., 220 U. S. 61, 78 (1911).26 If increasing age brings with it increasing susceptibility to physical difficulties, as the District Court was apparently willing to assume, the fact that individual Foreign Service employees may be able to perform past age 60 does not invalidate § 632 any more than did the similar truth undercut compulsory retirement at age 50 for uniformed state police in Murgia. Because Congress desired to maintain the competence of the Foreign Service, the mandatory retirement age of 60 rationally furthers *109its legitimate objective, and it makes no difference that some Foreign Service personnel may not be subject to the rigors of overseas service or that some Civil Service employees serve in various hardship positions in foreign lands.

We accept such imperfection because it is in turn rationally related to the secondary objective of legislative convenience. The Foreign Service retirement system and the Civil Service retirement system are packages of benefits, requirements, and restrictions serving many different purposes. When Congress decided to include groups of employees within one system or the other, it made its judgments in light of those amalgamations of factors. Congress was entitled to conclude that certain groups of employees share more characteristics with Foreign Service officers than with Civil Service personnel even though not serving for as long in as important overseas posts, and that other employees share more characteristics with Civil Service personnel than with Foreign Service officers even though serving some time in some overseas positions. Congress chose not to examine exactly which individual employees are likely to serve long enough in important enough positions in demanding enough locales to warrant mandatory early retirement. Rather than abandoning its primary end completely, or unnecessarily including all federal employees within the means, it drew a line around those groups of employees it thought most generally pertinent to its' objective. Whether we, or the District Court, think Congress was unwise in not choosing a means more precisely related to its primary purpose is irrelevant. Califano v. Jobst, 434 U. S. 47, 56-58 (1977); New Orleans v. Dukes, 427 U. S. 297, 303 (1976).

IV

Despite all this, appellees urge us to affirm the judgment on a basis not relied upon by the District Court: that the mandatory retirement age of 60 has no relation to the objective of reliable service in important foreign posts because *110overseas conditions often are not in fact more taxing than those in the United States and because arriving at 60 has an insufficient relationship to reduced physical and mental potential.27

Appellees rely in particular on the posture of the case— cross motions for summary judgment. They point out that their affidavits state that many overseas posts are as comfortable and safe as any in the United States; that many Foreign Service personnel under 60 have health problems; that employees just under the mandatory retirement age fill their fair share of hardship posts; and that age is not related to susceptibility to certain diseases and ailments' commonly linked to life overseas.

Appellees seem to believe that appellants had" to have current empirical proof that health and energy tend to decline somewhat by age 60 and had to offer such proof for the District Court’s perusal before the statute could be sustained.28 Such evidence of course would argue powerfully for sustaining the statute, see Murgia, 427 U. S., at 314-315, n. 7. But this case, as equal protection cases recurringly do, involves a legislative classification contained in a statute. In ordinary civil litigation, the question frequently is which party has *111shown that a disputed historical fact is more likely than not to be true. In an equal protection case of this type, however, those challenging the legislative judgment must convince the court that the legislative facts on which the classification is apparently based could not reasonably be conceived to be true by the governmental decisionmaker. Lindsley v. Natural Carbonic Gas Co., 220 U. S., at 78-79; accord, Schilb v. Kuebel, 404 U. S. 357, 364 (1971); United States v. Maryland Savings-Share Ins. Corp., 400 U. S. 4, 6 (1970); see McGinnis v. Royster, 410 U. S. 263, 274 (1973) (finding that the legislature “could have concluded rationally that” certain facts were true); Williamson v. Lee Optical Co., 348 U. S. 483, 487 (1955). As we have said in a slightly different context:

“The District Court’s responsibility for making ‘findings of fact’ certainly does not authorize it to resolve conflicts in the evidence against the legislature’s conclusion or even to reject the legislative judgment on the basis that without convincing statistics in the record to support it, the legislative viewpoint constitutes nothing more than what the District Court in this case said was ‘pure speculation.’ ” Firemen v. Chicago, R. I. & P. R. Co., 393 U. S., at 138-139.

Consequently, appellees were required to demonstrate that Congress has no reasonable basis for believing that conditions overseas generally are more demanding than conditions in the United States and that at age 60 or before many persons begin something of a decline in mental and physical reliability. Appellees have not satisfied these requirements. They say that many overseas posts are as pleasant as those in the United States and that many people over age 60 are healthy and many younger people are not.29 But they admit that age *112does in fact take its toll, and that Congress could perhaps have rationally chosen age 70 as the cutoff. Brief for Appel-lees 76-77; see Tr. of Oral Arg. 21-24, 27. And we have noted the common-sense proposition that aging — almost by definition — inevitably wears us all down.30 Murgia, supra, at 315. All appellees can say to this is that “[i]t can be reasonably argued that, given modem societal facts,” those between age 60 and 70 are as reliable as those under age 60. Brief for Appellees 76. But it is the very admission that the facts are arguable that immunizes from constitutional attack the congressional judgment represented by this statute:

“It makes no difference that the facts may be disputed or their effect opposed by argument and opinion of serious strength. It is not within the competency of the courts to arbitrate in such contrariety.” Rast v. Van Deman & Lewis Co., 240 U. S. 342, 357 (1916).

For these reasons, the judgment appealed from must be reversed.

So ordered.

dissenting.

The Court today finds a rational basis for the forced retirement of Foreign Service personnel at age 60, on a record devoid of evidence that persons of that age or older are less capable of performing their jobs than younger employees. I adhere to my view in Massachusetts Bd. of Retirement v. Murgia, 427 U. S. 307, 317-327 (1976) (Marshall, J., dissenting), that mandatory retirement provisions warrant more than this minimal level of equal protection review. Because *113I believe that the statute at issue here cannot withstand closer scrutiny, I respectfully dissent.

I

A person’s interest in continued Government employment, although not “fundamental” as the law now stands, certainly ranks among the most important of his personal concerns that Government action would be likely to affect. Id., at 322-323; cf. Arnett v. Kennedy, 416 U. S. 134 (1974); Board of Regents v. Roth, 408 U. S. 564, 572 (1972); Smith v. Texas, 233 U. S. 630, 636, 641 (1914). This interest is of special significance to older employees, because

“[o]nce terminated, the elderly cannot readily find alternative employment. The lack of work is not only economically damaging, but emotionally and physically draining. Deprived of his status in the community and of the opportunity for meaningful activity, fearful of becoming dependent on others for his support, and lonely in his new-found isolation, the involuntarily retired person is susceptible to physical and emotional ailments as a direct consequence of his enforced idleness. Ample clinical evidence supports the conclusion that mandatory retirement poses a direct threat to the health and life expectancy of the retired person . . . .” Massachusetts Bd. of Retirement v. Murgia, supra, at 323 (footnote omitted).

When legislative action affects individual interests of such dimension, a heightened level of judicial scrutiny is appropriate.

In addition, mandatory retirement provisions warrant careful judicial attention because of the class on which the deprivation is imposed. To be sure, the elderly are not a “discrete and insular minorit[y],” United States v. Carolene Products Co., 304 U. S. 144, 153 n. 4 (1938),1 in need of *114“extraordinary protection from the majoritarian political process.” San Antonio School Dist. v. Rodriguez, 411 U. S. 1, 28 (1973). But they have suffered from discrimination based upon generalizations that are inaccurate for many, if not most, of the age group affected. See Report of the Secretary of Labor to the Congress on Age Discrimination in Employment Under Section 715 of the Civil Rights Act of 1964, The Older American Worker 8 (1965) (hereinafter Labor Report); 113 Cong. Rec. 34742 (1967) (remarks of Rep. Burke); H. R. Rep. No. 95-527, pt. 1, p. 2 (1977); Note, The Cost of Growing Old: Business Necessity and the Age Discrimination in Employment Act, 88 Yale L. J. 565, 576-577 (1979), and sources cited therein. Such generalizations stigmatize the aged as physically and mentally deficient, regardless of their individual capabilities. Cf. House Select Committee on Aging, Mandatory Retirement: The Social and Human Cost of Enforced Idleness, 95th Cong., 1st Sess., 35, 37 (Comm. Print 1977) (hereafter House Select Committee on Aging); C. Edel-man & I. Siegler, Federal Age Discrimination in Employment Law 15-17 (1978) (hereafter Edelman & Siegler). Particularly in the area of employment, significant deprivations have been imposed on the basis of these stereotypes, see 29 U. S. C. § 621 (a); Labor Report 18-19; Note, The Age Discrimination in Employment Act of 1967, 90 Harv. L. Rev. 380, 380-381, 383 (1976).2

*115Considering the importance of the interests at stake and the prevalence of discrimination against the aged, I cannot agree that the glancing oversight of the rational-basis test fulfills our obligation to ensure that all persons receive the equal protection of the laws. I would require proof that the Foreign Service’s mandatory retirement scheme “serves important governmental objectives and [is] substantially related to achievement of those objectives.” Califano v. Webster, 430 U. S. 313, 316-317 (1977); Craig v. Boren, 429 U. S. 190, 197 (1976); Massachusetts Bd. of Retirement v. Murgia, 427 U. S., at 325 (Marshall, J., dissenting). Measured by this standard, the Foreign Service’s mandatory retirement provisions must fall.

II

Before applying this intermediate standard, it is first necessary to determine the nature of the classifications that the statute delimits. In this case, there are two. The statutory scheme distinguishes between civil servants and Foreign Service personnel and between Foreign Service employees under 60 and those 60 or over. Appellees unequivocally claimed in this Court that the latter distinction was unconstitutional, see Brief for Appellees 76-78; Tr. of Oral Arg. 26-28, as the Court seems to concede, ante, at 109-110, and n. 27. Nonetheless the Court summarily dismisses this claim, finding that ap-*116pellees abandoned it below after the judgment of the District Court had issued.

By limiting its consideration of the classifications at issue, the majority has evaded the more difficult question in this case. This Court has repeatedly held that a “prevailing party may . . . assert in a reviewing court any ground in support of his judgment, whether or not that ground was relied upon or even considered by the trial court.” Dandridge v. Williams, 397 U. S. 471, 475 n. 6 (1970); accord, California Bankers Assn. v. Shultz, 416 U. S. 21, 71 (1974); Langnes v. Green, 282 U. S. 531, 538-539 (1931); United States v. American Railway Express Co., 265 U. S. 425, 435 (1924).3 The judgment of the District Court was that § 632 of the Foreign Service Act of 1946, 22 U. S. C. § 1002, “violates the equal protection guarantees embodied in the Fifth Amendment.” App. to Juris. Statement 9A. Appellees’ contention that the statute discriminates against persons aged 60 and over patently is a ground for affirming that judgment. Whether ap-pellees previously abandoned the issue is irrelevant since the purported abandonment came after the District Court had granted summary judgment. Because the Government had the opportunity to present evidence on the issue, it could in no way be prejudiced by its resurrection here. Thus, the claim is properly before us.

Ill

Undoubtedly, an important objective of the Foreign Service retirement system is to assure the “professional competence” *117of the Foreign Service corps. See ante, at 97. The Court finds that mandatory retirement at age 60 is rationally related to this objective in two ways. In the Court’s view, the physical and psychological difficulties that Foreign Service personnel face as a result of frequent overseas assignments impair their performance at an earlier age than most persons including, it seems, civil servants exposed to much the same conditions. Hence, the majority concludes, Congress could reasonably have determined that 60-year-olds would lack the vitality necessary to perform their jobs competently. The Court also finds that the early retirement age creates “room at the top,” thereby ensuring a predictable supply of promotion opportunities for younger employees. Such opportunities, it is said, are necessary to “spur morale and stimulate superior performance in the ranks.” Ante, at 98. A fair reading of the record before us, however, reveals no substantial relationship between the mandatory retirement system and the articulated objective of the statutory scheme.

A

In my judgment, appellees have successfully challenged the Government’s central premise that the pressures of transient Foreign Service life diminish the capacity of older employees to perform their jobs. There is nothing inherent in any of the positions that appellees hold to indicate that early retirement is necessary to ensure excellence. Foreign Service officers in the State Department engage in economic and political research, visa or other consular work, negotiations with representatives of foreign governments, personnel recruitment and management, and other administrative functions. See United States Dept. of State and International Communication Agency, Foreign Service Officer Careers 4-8 (1978). Officers in the International Communication Agency lecture and perform cultural and other informational duties, as well as administrative and personnel management functions. Id., *118at 8-10. The Agency for International Development (AID) employs economists, financial analysts, staff attorneys, auditors, and accountants in providing economic and technical assistance to other countries. U. S. Civil Service Comm’n, Federal Jobs Overseas 10-11 (1975). The mandatory retirement provisions in addition cover Foreign Service staff personnel who perform technical, administrative, clerical, or custodial work. See H. R. Rep. No. 2104, 86th Cong., 2d Sess., 15 (1960).4

That older workers could effectively perform such Foreign Service jobs is also suggested by the lack of an early mandatory retirement provision for civil servants who spend much of their careers abroad doing work similar to that of Foreign Service personnel. Of the over 58,000 American civilians in Government positions overseas in 1976, only the 4,787 Foreign Service personnel faced mandatory retirement at age 60. 436 F. Supp. 134, 136 (DC 1977). Moreover, discrete segments of this work force, such as the Agriculture Department’s Foreign Service, spend almost as much of their tenure overseas as do members of the State Department’s Foreign Service. Id., at 137. The Court discounts these figures because it finds that the need for excellence in the Foreign Service may be more compelling than in the Civil Service. Ante, at 106. However, almost 40% of the Americans working overseas for Foreign Service agencies are civil servants who are not subject to forced retirement, and AID often has its work performed on a contract basis by other agencies that do not have mandatory retirement provisions. 436 F. Supp., at 136-137; see §5, 92 Stat. 191. Despite this broad experience with older workers in *119analogous situations, the Government submitted no evidence that it has encountered age-related problems in connection with these or other civil servants aged 60 and over.

Appellees, on the other hand, introduced a substantial amount of medical testimony dispelling any adverse correlation between job performance and advancing age, and offered to introduce more. For example, the former chief psychiatrist for the Peace Corps stated flatly that “inability to perform work satisfactorily under stressful conditions in overseas cultures has no relationship to advancing age.” Affidavit of Dr. J. English 2. See also Affidavit of Dr. D. Kessler; Affidavit of T. Fox.5 Similarly, appellees have pointed to a variety of studies indicating that older workers may be more competent than younger ones in the types of jobs involved in this case. The House Report accompanying the recent amendments to the Age Discrimination in Employment Act, H. R. Rep. No. 95-527, pt. 1, p. 4 (1977), noted:

“Testimony to the committee cited the results of various research findings which indicate that older workers were as good or better than their younger coworkers with regard to dependability, judgment, work quality, work volume, human relations, and absenteeism; and older workers were shown to have fewer accidents on the job. As Congressman Pepper stated before our committee: ‘The Labor Department’s finding that there is more variation in work ability within the same age group than between age groups justifies judging workers on competency, not age.’ ” (Footnote omitted.)

*120The House Select Committee on Aging 34 also observed:

“Studies by the Department of Labor, the late Ross McFarland of the Harvard School of Public Health, the National Council on the Aging, and many other experts in the field indicate that older workers can produce a quality and quantity of work equal or superior to younger workers, that they have as good, and usually better, attendance records as younger workers, that they are as capable of learning new skills and adapting to changing circumstances when properly presented as younger workers, and that they are generally more satisfied with their jobs than younger workers.”

See also Report of the Secretary of Labor to the Congress Under Section 715 of the Civil Rights Act of 1964: Research Materials 86 (1965); Edelman & Siegler 27-31; Note, 88 Yale L. J., at 576-577, and sources cited therein.

The Court closes its eyes to appellees’ evidence against the mandatory retirement provision and excuses the Government from producing evidence in support of it because Congress determined that the nomadic life of Foreign Service personnel would take its toll by the age of 60. This determination, the Court concludes, rested on the “common-sense proposition that aging — almost by definition — inevitably wears us all down.” Ante, at 112.6 The issue, however, is not whether persons *121between age 60 and 70 “wear down,” but whether they are competent Foreign Service personnel. Absent any concrete evidence in the record that they are less able, or indeed, any indication that Congress even considered such information when it enacted the statute, see n. 6, supra, the Court is remitted to unsubstantiated assumptions concerning the competency of older workers for white-collar jobs.

With respect to sex discrimination, we have refused to accept “ ‘overbroad’ generalizations” about the characteristics of a particular class as substantial support for a legislative classification. See Califano v. Goldfarb, 430 U. S. 199, 211 (1977) (plurality opinion); Craig v. Boren, 429 U. S., at 198-199; Stanton v. Stanton, 421 U. S. 7 (1975); Frontiero v. Richardson, 411 U. S. 677 (1973). I believe the same rule should apply here. See supra, at 113-115. While age, unlike sex, is at some point likely to bear a relationship to ability, I would require a showing that a substantial relationship does in fact exist. Thus, to the extent that Congress in § 632 viewed age as predictive of a decline in competence, this Court should not simply assume the correlation, but should inquire whether age is a sufficiently accurate predictor to justify the significant deprivations imposed by forced retirement. See Craig v. Boren, supra, at 201-202.7 Since ap-*122pellees have adduced considerable evidence demonstrating the absence of any correlation, and the Government has presented no evidence to the contrary, the record simply does not support the Court’s result.

Not only is mandatory retirement an insufficiently accurate predictor of competence, it is also an unnecessary one. As the Foreign Service personnel system now operates, persons who do not measure up to Service standards are selected out, or terminated, after an annual review. Ante, at 99. Further, all Foreign Service employees are given biennial medical examinations, as well as special examinations when necessary, and are subject to medical selection out if they are not fit for duty. See Record 20. Under this scheme, then, the continued competence of appellants’ personnel is periodically assessed. With such individualized procedures already in effect, the Government cannot realistically claim that prohibiting resort to age-based generalizations would jeopardize the quality of the Foreign Service. Cf. United States Dept. of Agriculture v. Murry, 413 U. S. 508, 518-519 (1973) (Marshall, J., concurring); Craig v. Boren, supra, at 199.

B

The other ground on which the Court upholds mandatory retirement is its function of

“stimulating the highest performance in the ranks of the Foreign Service by assuring that opportunities for promotion would be available despite limits on the number of personnel classes and on the number of positions in the *123Service. Aiming at superior achievement can hardly be characterized as illegitimate, and it is equally untenable to suggest that providing promotion opportunities through the selection-out process and through early retirement does not play an acceptable role in the process.” Ante, at 101.

This justification, it seems to me, would legitimate any retirement system in which there are a limited number of high-level positions. Indeed, the Court acknowledges as much when it deems the rationale equally applicable to Foreign Service staff personnel, who were not designated by Congress as an elite cadre but who are nonetheless subject to the mandatory retirement provisions. Ante, at 99-100, n. 15. The fundamental flaw in this analysis is that the Court ends rather than begins its inquiry by articulating the legislative goal of a competent Foreign Service. See Trimble v. Gordon, 430 U. S. 762, 769 (1977). The question that the majority fails to pursue is whether, on balance, mandatory retirement at 60 substantially furthers this goal.

The answer is not readily apparent, for even if mandatory retirement does ensure promotional opportunities for younger employees, it also deprives the Service of the talents of persons who it has admitted are, at least at the time of their retirement, “its best officers.” S. Doe. No. 14, 90th Cong., 1st Sess., 118 (1967). In the absence of any evidence that employees aged 60 and over are less able, or that forced retirement does in fact boost productivity by enhancing recruitment and promotional opportunities, this proffered justification does not withstand analysis.

Moreover, appellees note that most Foreign Service officers, prompted by the generous pension benefits offered by the Service, retire well before the age of 60. See Record 20. The experience of the Civil Service and private employers suggests that this pattern would not change significantly were the mandatory retirement age raised. See U. S. Civil Service *124Comm’n, Federal Fringe Benefit Facts 16-17, 22 (1977); Retirement Age Policies: Hearing before the House Select Committee on Aging, 95th Cong., 1st Sess., pt. 1, p. 30 (1977).8 Thus, it cannot be assumed that, absent § 632, many Foreign Service personnel would stay on to “clog the promotional stream” for younger persons, particularly since those who remain would still be subject to selection out for health reasons, poor performance, or nonpromotion.

IV

I do not disagree, of course, that Congress could legitimately take “great pains to assure the high quality of those occupying positions critical to the conduct of our foreign relations in the post-war world.” Ante, at 101. Nor do I contend that this Court should substitute its judgment for that of the Congress or the Foreign Service on the appropriate retirement system for Foreign Service personnel. I submit, however, that it is the function of this Court to assess constitutional challenges to that system on the record before us. Appellees presented substantial evidence that the mandatory retirement provision has not accomplished the purposes for which it was designed. The Government failed to establish otherwise. Where individuals’ livelihood, self-esteem, and dignity are so critically affected, I do not believe the Government should be relieved of that responsibility.

Accordingly, I dissent.