*523Justice Blackmun

delivered the opinion of the Court.

This case concerns a facial challenge to the method used by the Secretary of Health and Human Services to determine whether a child is “disabled” and therefore eligible for benefits under the Supplemental Security Income Program, Title XVI of the Social Security Act, as added, 86 Stat. 1465, and amended, 42 U. S. C. § 1381 et seq. (1982 ed. and Supp. V).

*524f — Í

In 1972, Congress enacted the Supplemental Security Income (SSI) Program to assist “individuals who have attained age 65 or are blind or disabled” by setting a guaranteed minimum income level for such persons. 42 U. S. C. § 1381 (1982 ed.). The program went into effect January 1, 1974. Currently, about 2 million claims for SSI benefits are adjudicated each year. Of these, about 100,000 are child-disability claims.1

A person is eligible for SSI benefits if his income and financial resources are below a certain level, § 1382(a), and if he is “disabled.” Disability is defined in § 1382c(a)(3) as follows:

“(A) An individual shall be considered to be disabled for purposes of this subchapter if he is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than twelve months (or, in the case of a child under the age of 18, if he suffers from any medically determinable physical or mental impairment of comparable severity).

“(B) For purposes of subparagraph (A), an individual shall be determined to be under a disability only if his physical or mental impairment or impairments are of such severity that he is not only unable to do his previous work but cannot, considering his age, education, and work experience, engage in any other kind of substantial gainful work which exists in the national economy ....

“(C) For purposes of this paragraph, a physical or mental impairment is an impairment that results from anatomical, physiological, or psychological abnormalities which are demonstrable by medically acceptable clinical and laboratory diagnostic techniques.”

*525This statutory definition of disability was taken from Title II of the Social Security Act, 70 Stat. 815, as amended, 42 U. S. C. §423 et seq. (1982 ed. and Supp. V) (providing for payment of insurance benefits to disabled workers who have contributed to the Social Security Program). See §§ 423(d)(1)(A) and (d)(2)(A) (definitions of disability).

Pursuant to his statutory authority to implement the SSI Program,2 the Secretary has promulgated regulations creating a five-step test to determine whether an adult claimant is disabled. See Bowen v. Yuckert, 482 U. S. 137, 140-142 (1987).3 The first two steps involve threshold determinations that the claimant is not presently working and has an impairment which is of the required duration and which significantly limits his ability to work. See 20 CFR § § 416.920(a) through (c) (1989). In the third step, the medical evidence of the claimant’s impairment is compared to a list of impairments presumed severe enough to preclude any gainful work. See 20 CFR pt. 404, subpt. P, App. 1 (pt. A) (1989). If the claimant’s impairment matches or is “equal” to one of the listed impairments, he qualifies for benefits without further inquiry. § 416.920(d). If the claimant cannot qualify under the listings, the analysis proceeds to the fourth and fifth steps. At these steps, the inquiry is whether the claimant can do his own past work or any other work that exists in the *526national economy, in view of his age, education, and work experience. If the claimant cannot do his past work or other work, he qualifies for benefits. §§ 416.920(e) and (f).

The Secretary’s test for determining whether a child claimant is disabled is an abbreviated version of the adult test. A child qualifies for benefits if he “is not doing any substantial gainful activity,” § 416.924(a), if his impairment meets the duration requirement, § 416.924(b)(1), and if it matches or is medically equal to a listed impairment, §§416.924(b)(2) and (3). In evaluating a child’s claim, both the general listings and a special listing of children’s impairments, 20 CFR pt. 404, subpt. P, App. 1 (pt. B) (1989), are considered. If a child cannot qualify under these listings, he is denied benefits. There is no further inquiry corresponding to the fourth and fifth steps of the adult test.

hH

Respondent Brian Zebley, a child who had been denied SSI benefits, brought a class action in the United States District Court for the Eastern District of Pennsylvania to challenge the child-disability regulations.4 His complaint alleges that the Secretary

“has promulgated regulations and issued instructions .. . whereby children have their entitlement to SSI disability benefits based solely on the grounds that they have a listed impairment or the medical equivalent of a listed impairment ... in contravention of the Act’s requirement that a child be considered disabled ‘if he suffers from any medically determinable physical or mental impairment of comparable severity’ to that which disables *527an adult under the program.” Complaint in Civil Action No. 83-3314, ¶2.

The District Court, on January 10, 1984, certified a class of all persons “who are now, or who in the future will be, entitled to an administrative determination ... as to whether supplemental security income benefits are payable on account of a child who is disabled, or as to whether such benefits have been improperly denied, or improperly terminated, or should be resumed.” App. 26, 27.

The court in due course granted summary judgment in the Secretary’s favor as to the class claims, ruling that the regulations are not “facially invalid or incomplete . . . and permit] the award of benefits in conformity with the intent of Congress.” Zebley v. Heckler, 642 F. Supp. 220, 222 (1986). The Court of Appeals for the Third Circuit vacated in part that summary judgment. Zebley ex rel. Zebley v. Bowen, 855 F. 2d 67 (1988). The Third Circuit found the Secretary’s regulatory scheme for child-disability benefits inconsistent with the statute because the listings-only approach of the regulations does not account for all impairments of “comparable severity” and denies child claimants the individualized functional assessment that the statutory standard requires and that the Secretary provides to adults. Id., at 69. Although the Court of Appeals recognized that the Secretary’s interpretation of the statute is entitled to deference, it rejected the regulations as contrary to clear congressional intent. The court remanded the case to the District Court with the direction that summary judgment be entered in favor of the plaintiff class on the claim that the Secretary must give child claimants an opportunity for individualized assessment of their functional limitations. Id., at 77. We granted certiorari to resolve a conflict among the Circuits as to the validity of the Secretary’s approach to child disability. 490 U. S. 1064 (1989).5

*5281 í — Í H-I

Since the Social Security Act expressly grants the Secretary rulemaking power, see n. 2, supra, “ ‘our review is limited to determining whether the regulations promulgated exceeded the Secretary’s statutory authority and whether they are arbitrary and capricious.’” Yuckert, 482 U. S., at 145 (quoting Heckler v. Campbell, 461 U. S. 458, 466 (1983)); see Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 843-844 (1984) (“If Congress has explicitly left a gap for the agency to fill, there is an express delegation of authority to the agency to elucidate a specific provision of the statute by regulation. Such legislative regulations are given controlling weight unless they are arbitrary, capricious, or manifestly contrary to the statute”). We conclude, however, that the Secretary’s child-disability regulations cannot be reconciled with the statute they purport to implement.

The statute generally defines “disability” in terms of an individualized, functional inquiry into the effect of medical problems on a person’s ability to work. Yuckert, 482 U. S., at 146 (Social Security Act adopts “functional approach”); Campbell, 461 U. S., at 459-460, 467 (Act “defines ‘disability’ in terms of the effect a physical or mental impairment has on a person’s ability to function in the workplace”; “statutory scheme contemplates that disability hearings will be individualized determinations”).

*529The statutory standard for child disability is explicitly linked to this functional, individualized standard for adult disability. A child is considered to be disabled “if he suffers from any . . . impairment of comparable severity” to one that would render an adult “unable to engage in any substantial gainful activity.” 42 U. S. C. § 1382c(a)(3)(A) (1982 ed.). The next paragraph of the statute elaborates on the adult disability standard, providing that an adult is considered unable to engage in substantial gainful activity, and is therefore disabled, if he is unable to do either his own past work or other work. § 1382c(a)(3)(B). In plain words, the two provisions together mean that a child is entitled to benefits if his impairment is as severe as one that would prevent an adult from working.

The question presented is whether the Secretary’s method of determining child disability conforms to this statutory standard. Respondents argue, and the Third Circuit agreed, that it does not, because the regulatory requirement that a child claimant’s impairment must match or be equivalent to a listed impairment denies benefits to those children whose impairments are severe and disabling even though the impairments are not listed and cannot meaningfully be compared with the listings. The Secretary concedes that his listings do not cover every impairment that could qualify a child for benefits under the statutory standard, but insists that the listings, together with the equivalence determination, see 20 CFR § 416.924(b)(3) (1989), are sufficient to carry out the statutory mandate that children with impairments of “comparable severity” shall be considered disabled. To decide this question, we must take a closer look at the regulations at issue.

IV

The listings set out at 20 CFR pt. 404, subpt. P, App. 1 (pt. A) (1989), are descriptions of various physical and mental illnesses and abnormalities, most of which are categorized by *530the body system they affect.6 Each impairment is defined in terms of several specific medical signs, symptoms, or laboratory test results.7 For a claimant to show that his impairment matches a listing, it must meet all of the specified medical criteria. An impairment that manifests only some of those criteria, no matter how severely, does not qualify.8 See Social Security Ruling (SSR) 83-19,9 Dept, of Health and Human Services Rulings 90 (Jan. 1983) (“An impairment ‘meets’ a listed condition . . . only when it manifests the specific findings described in the set of medical criteria for that listed impairment.” “The level of severity in any particular *531listing section is depicted by the given set of findings and not by the degree of severity of any single medical finding — no matter to what extent that finding may exceed the listed value”). Id., at 91. (Emphasis in original.)

For a claimant to qualify for benefits by showing that his unlisted impairment, or combination of impairments, is “equivalent” to a listed impairment, he must present medical findings equal in severity to all the criteria for the one most similar listed impairment.10 20 CFR § 416.926(a) (1989) (a claimant’s impairment is “equivalent” to a listed impairment “if the medical findings are at least equal in severity” to the medical criteria for “the listed impairment most like [the claimant’s] impairment”); SSR 83-19, at 91 (a claimant’s impairment is “equivalent” to a listing only if his symptoms, signs, and laboratory findings are “at least equivalent in severity to” the criteria for “the listed impairment most like the individual’s impairment(s)”; when a person has a combination of impairments, “the medical findings of the combined impairments will be compared to the findings of the listed impairment most similar to the individual’s most severe impairment”).11 A claimant cannot qualify for benefits under the “equivalence” step by showing that the overall functional impact of his unlisted impairment or combination of impairments is as severe as that of a listed impairment. SSR 83-19, at 91-92 (“[I]t is incorrect to consider whether the listing is equaled on the basis of an assessment of overall func*532tional impairment. . . . The functional consequences of the impairments . . . irrespective of their nature or extent, cannot justify a determination of equivalence”) (emphases in original).

The Secretary explicitly has set the medical criteria defining the listed impairments at a higher level of severity than the statutory standard. The listings define impairments that would prevent an adult, regardless of his age, education, or work experience, from performing any gainful activity, not just “substantial gainful activity.” See 20 CFR § 416.925(a) (1989) (purpose of listings is to describe impairments “severe enough to prevent a person from doing any gainful activity”); SSR 83-19, at 90 (listings define “medical conditions which ordinarily prevent an individual from engaging in any gainful activity”). The reason for this difference between the listings’ level of severity and the statutory standard is that, for adults, the listings were designed to operate as a presumption of disability that makes further inquiry unnecessary. That is, if an adult is not actually working and his impairment matches or is equivalent to a listed impairment, he is presumed unable to work and is awarded benefits without a determination whether he actually can perform his own prior work or other work. See Yuckert, 482 U. S., at 141 (if an adult’s impairment “meets or equals one of the listed impairments, the claimant is conclusively presumed to be disabled. If the impairment is not one that is conclusively presumed to be disabling, the evaluation proceeds to the fourth step”); id., at 153 (the listings “streamlin[e] the decision process by identifying those claimants whose medical impairments are so severe that it is likely they would be found disabled regardless of their vocational background”); Bowen v. City of New York, 476 U. S. 467, 471 (1986) (“If a claimant’s condition meets or equals the listed impairments, he is conclusively presumed to be disabled and entitled to benefits”; if not, “the process moves to the fourth step”); Campbell, 461 U. S., at 460 (“The regulations recognize-that *533certain impairments are so severe that they prevent a person from pursuing any gainful work. ... A claimant who establishes that he suffers from one of these impairments will be considered disabled without further inquiry. ... If a claimant suffers from a less severe impairment, the Secretary must determine whether the claimant retains the ability to [work]”).

When the Secretary developed the child-disability listings, he set their medical criteria at the same level of severity as that of the adult listings. See 42 Fed. Reg. 14705 (1977) (the child-disability listings describe impairments “of ‘comparable severity’ to the adult listing”); SSA Disability Insurance Letter12 No. Ill — 11 (Jan. 9, 1974), App. 97 (child-disability listings describe impairments that affect children “to the same extent as . . . the impairments listed in the adult criteria” affect adults’ ability to work).

Thus, the listings in several ways are more restrictive than the statutory standard. First, the listings obviously do not cover all illnesses and abnormalities that actually can be disabling. The Secretary himself has characterized the adult listing as merely containing “over 100 examples of medical conditions which ordinarily prevent” a person from working, and has recognized that “it is difficult to include in the listing all the sets of medical findings which describe impairments severe enough to prevent any gainful work.” SSR 83-19, at 90 (emphasis added). See also 50 Fed. Reg. 50068, 50069 (1985) (listings contain only the most “frequently diagnosed” impairments); 44 Fed. Reg. 18170, 18175 (1979) (“The Listing criteria are intended to identify the more commonly occurring impairments”). Similarly, when the Secretary published the child-disability listings for comment in 1977, he described them as including only the “more common impairments” affecting children. 42 Fed. Reg. 14706 (the child-*534disability listings “provide a means to efficiently and equitably evaluate the more common impairments”).13

Second, even those medical conditions that are covered in the listings are defined by criteria setting a higher level of severity than the statutory standard, so they exclude claimants who have listed impairments in a form severe enough to preclude substantial gainful activity, but not quite severe enough to meet the listings level — that which would preclude any gainful activity. Third, the listings also exclude any claimant whose impairment would not prevent any and all persons from doing any kind of work, but which actually precludes the particular claimant from working, given its actual effects on him — such as pain, consequences of medication, and other symptoms that vary greatly with the individual14— and given the claimant’s age, education, and work experience. Fourth, the equivalence analysis excludes claimants who have unlisted impairments, or combinations of impairments, that do not fulfill all the criteria for any one listed impairment. Thus, there are several obvious categories of claimants who would not qualify under the listings, but who nonetheless would meet the statutory standard.

For adults, these shortcomings of the listings are remedied at the final, vocational steps of the Secretary’s test. A *535claimant who does not qualify for benefits under the listings, for any of the reasons described above, still has the opportunity to show that his impairment in fact prevents him from working. 20 CFR §§416.920(e) and (f) (1989); Yuckert, 482 U. S., at 141 (if an adult claimant’s “impairment is not one that is conclusively presumed to be disabling, the evaluation proceeds” to the fourth and fifth steps); Campbell, 461 U. S., at 460 (“If a claimant suffers from a less severe impairment” than the listed impairments, “the Secretary must determine whether the claimant retains the ability to perform either his former work or some less demanding employment”).15

For children, however, there is no similar opportunity. Children whose impairments are not quite severe enough to rise to the presumptively disabling level set by the listings; children with impairments that might not disable any and all children, but which actually disable them, due to symptomatic effects such as pain, nausea, side effects of medication, etc., or due to their particular age, educational background, and circumstances; and children with unlisted impairments or combinations of impairments16 that are not equivalent to any one listing — all these categories of child claimants are simply *536denied benefits, even if their impairments are of “comparable severity” to ones that would actually (though not presumptively) render an adult disabled.17

The child-disability regulations are simply inconsistent with the statutory standard of “comparable severity.”18 This in*537consistency is aptly illustrated by the fact that the Secretary applies the same approach to child-disability determinations under Title XVI and to widows’ and widowers’ disability benefits under Title II, despite the fact that Title II sets a stricter standard for widows’ benefits. Under the Secretary’s regulations and rulings, both widows and children qualify for benefits only if the medical evidence of their impairments meets or equals a listing. SSR 83-19, at 93. Title II provides: “A widow. . . [or] widower shall not be determined to be under a disability . . . unless his or her . . . impairment or impairments are of a level of severity which under regulations prescribed by the Secretary is deemed to be sufficient to preclude an individual from engaging in any gainful activity.” 42 U. S. C. § 423(d)(2)(B) (1982 ed., Supp. V). When Congress set out to provide disabled children with benefits, it chose to link the disability standard not to this test, but instead to the more liberal test set forth in § 423(d)(2)(A) and in § 1382c(a)(3)(A) (any impairment making a claimant “unable to engage in any substantial gainful activity” qualifies him for benefits). The Secretary’s regulations, treating child-disability claims like claims for widows’ benefits, nullify this congressional choice. See Yuckert, 482 U. S., at 163-164 (dissenting opinion) (contrasting widows’ disability statute with the § 423(d)(2)(A)/§ 1382c(a)(3) test, which requires an individualized inquiry as to whether the claimant can work); S. Rep. No. 744, 90th Cong., 1st Sess., 49 (1967) (disabled widows’ statutory “test of disability ... is somewhat more restrictive than that for disabled workers”).19

*538V

The Secretary does not seriously dispute the disparity in his approach to child- and adult-disability determinations. *539He argues, instead, that the listings-only approach is the only-practicable way to determine whether a child’s impairment is “comparable” to one that would disable an adult. An individualized, functional approach to child-disability claims like that provided for adults is not feasible, the Secretary asserts, since children do not work; there is no available measure of their functional abilities analogous to an adult’s ability to work, so the only way to measure “comparable severity” is to compare child claimants’ medical evidence with the standard of severity set by the listings. Laying to one side the obvious point that such a comparison does not properly implement the statute because the Secretary’s current listings set a level of severity higher than that prescribed by the statute, this argument still is not persuasive. Even if the listings were set at the same level of severity as the statute, and expanded to cover many more childhood impairments, no set of listings could ensure that child claimants would receive benefits whenever their impairments are of “comparable severity” to ones that would qualify an adult for benefits under the individualized, functional analysis contemplated by the statute and provided to adults by the Secretary. No decision process restricted to comparing claimants’ medical evidence to a fixed, finite set of medical criteria can respond adequately to the infinite variety of medical conditions and combinations thereof, the varying impact of such conditions due to the claimant’s individual characteristics, and the constant evolution of medical diagnostic techniques.

The Secretary’s claim that a functional analysis of child-disability claims is not feasible is unconvincing. The fact that a vocational analysis is inapplicable to children does not *540mean that afunctional analysis cannot be applied to them. An inquiry into the impact of an impairment on the normal daily activities of a child of the claimant’s age — speaking, walking, washing, dressing, feeding oneself, going to school, playing, etc. —is, in our view, no more amorphous or unmanageable than an inquiry into the impact of an adult’s impairment on his ability to perform “any other kind of substantial gainful work which exists in the national economy,” § 1382c(a)(3)(B).20 Moreover, the Secretary tacitly acknowledges that functional assessment of child claimants is possible, in that some of his own listings are defined in terms of functional criteria. See, e. g., 20 CFR pt. 404, subpt. P, App. 1 (pt. B), § 101.03 (1989) (listing for “Deficit of musculo-skeletal function” defined in terms of difficulty in walking or “[inability to perform age-related personal self-care activities involving feeding, dressing, and personal hygiene”); § 111.02(B) (listing for “Major motor seizures” defined in terms of “Significant interference with communication” or “Significant emotional disorder,” or “Where significant adverse effects of medication interfere with major daily activities”); § 112.05(C) (mental retardation listing for claimants with IQ of 60-69 requiring “a physical or other mental impairment imposing additional and significant restriction of function or developmental progression”).21 Also, the Secretary’s *541own test for cessation of disability involves an examination of a child claimant’s ability to “perform age-appropriate activities.” 20 CFR § 416.994(c) (1989). Finally, the Secretary’s insistence that child claimants must be assessed from “a medical perspective alone, without individualized consideration of . . . residual functional capacity,” Brief for Petitioner 45, seems to us to make little sense in light of the fact that standard medical diagnostic techniques often include assessment of the functional impact of the disorder.22

<1 I — I

We conclude that the Secretary’s regulations and rulings implementing the child-disability statute simply do not carry out the statutory requirement that SSI benefits shall be provided to children with “any . . . impairment of comparable severity” to an impairment that would make an adult “unable to engage in any substantial gainful activity.” § 1382c(a)(3)(A). For that reason, the Secretary’s approach to child disability is “manifestly contrary to the statute,” Chevron, 467 U. S., at 844, and exceeds his statutory authority.

The judgment of the Court of Appeals, vacating in part the District Court’s grant of summary judgment in the Secretary’s favor as to the claims of the plaintiff class, is affirmed.

It is so ordered.

Justice White,

with whom The Chief Justice joins, dissenting.

Only two Terms ago, when reviewing an aspect of the Secretary’s methodology for evaluating disability applications *542under this Act, we emphasized that “Congress has ‘conferred on the Secretary exceptionally broad authority’ ” in this context, and we stated that the Secretary’s regulations were therefore entitled to great deference. Bowen v. Yuckert, 482 U. S. 137, 145 (1987), quoting Heckler v. Campbell, 461 U. S. 458, 466 (1983). Because the majority has failed to abide by this principle, I respectfully dissent.

As this case involves a challenge to an agency’s interpretation of a statute that the agency was entrusted to administer, Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984), provides the framework for our review. We should therefore first ask whether Congress has expressed a clear intent on the question at issue here; if so, we should enforce that intent. If not, as I think is the case, we should defer to the agency’s interpretation as long as it is permissible. Id., at 842-845.

Section 1614(a)(3)(A) of the Social Security Act, 42 U. S. C. § 1382c(a)(3)(A) (1982 ed.), provides that a person is disabled if he is unable by reason of any medically determinable physical or mental impairment to engage in any substantial gainful employment; subsection (3)(B) further defines “disability” by providing that the impairment or impairments must be severe enough, considering the person’s age, education, and work experience, to prevent him from engaging in any kind of substantial gainful employment which exists in the national economy. The Secretary has implemented the statute with respect to adults by regulations listing certain impairments that he will, without more, consider disabling because each of them would prevent an adult from engaging in any kind of gainful employment. 20 CFR pt. 404, subpt. P, App. 1 (1989). If not suffering from one of those impairments or its equivalent, an adult is then given further consideration as required by subsection (a)(3)(B) in order to determine whether in light of his impairment and the specified nonmedical factors he could perform any substantial gainful activities in the national labor market.

*543At the end of 42 U. S. C. § 1382c(a)(3)(A) (1982 ed.), with its definition of disability, is a parenthetical provision defining that term in the case of persons under 18: “or, in the case of a child under the age of 18, if he suffers from any medically determinable physical or mental impairment of comparable severity.” There is no reference to nonmedical factors in this definition and no references to specific consequences that an impairment must or should produce. Furthermore, neither “comparable,” “severity,” nor the two words together are there or elsewhere defined in the Act, and their meaning is anything but clear. The severity of an impairment that disables an adult is measured by its effects on the ability to engage in gainful employment. But that yardstick is not useful with respect to children, whose inability to work is not due to mental or physical impairment, but to the stage of their development and the labor market. Given this task of comparing apples and oranges, it is understandable that the Secretary implemented the statute with respect to children in a somewhat different manner than he did for adults, and surely there is no direction in the statute to employ the same methodology for both groups.

Under the regulations applying to children, a person under 18 will be considered disabled if suffering from a Part A impairment listed for adults or its equivalent, as long as the disease’s processes have a similar effect on adults and younger persons. Because vocational considerations are largely beside the point in dealing with children — a fact that the Secretary submits Congress recognized in referring only to medical considerations in subsection (a)(3)(A)’s definition of what would disable a child — the regulations do not provide for further consideration of the child in light of such factors. Instead, a child not suffering from a Part A impairment is evaluated under an additional listing of impairments in Part B of Appendix 1 to subpart P, any of which, or its equivalent, will be deemed sufficient to disable a child. The preamble to Part B, published in 1977, 42 Fed. Reg. 14705, stated that in *544identifying medical criteria that would establish disability for a child, the Secretary had placed primary emphasis on the effects of physical and mental impairments in children, and the restrictions on growth, learning, and development imposed on the child by the impairments. The impairments that were determined to affect the child’s development to the same extent that the adult criteria have on an adult’s ability to engage in substantial gainful activity were deemed to be of “comparable severity” to the disabling adult impairments.

I do not find this approach to be an impermissible implementation of the rather ambiguous congressional directives with respect to children. Surely it cannot be said that the regulations, insofar as they use the Part A and Part B listings, singly or in combination, to identify disability in children, are inconsistent with the statute and void on their face. And as I understand it, no one claims that they are. What is submitted is, first, that the listings do not identify all of the specific medical impairments that should be considered disabling, and second, that each child not deemed disabled under Parts A and B must be evaluated in terms of both his or her medical impairments and nonmedical factors, as are adults.

These alleged deficiencies are said to be sufficient to invalidate the regulations on their face. But surely these claims, if true, only would demonstrate that the regulations do not go far enough. Furthermore, the claims purport to be supported by descriptions of various unlisted impairments and anecdotal evidence, none of which, it seems to me, has been adjudged by a court to be sufficient to demonstrate that the Part B impairments, or their equivalents, fail to identify impairments that will have comparably severe effects on a child’s development as the disabling impairments for an adult will have on an adult’s ability to engage in substantial gainful employment. If there are medically determinable diseases or impairments that should be considered disabling because of comparable severity to those affecting adults, the children *545suffering from them should claim disability, make their case before the Secretary, and take the case to court if their claims are rejected.1 As for the more general attack on the regulation — that they do not provide for individualized evaluation based on nonmedical factors —the Secretary contends that it is a reasonable construction of section 3(A) to confine disabling criteria to medical factors where children are concerned. In any event, rather than declaring the regulations wholly or partly void on their face, the Court would be better advised to insist on children making out their claims in individual cases; only then can a court confidently say that the medically identifiable impairment, though neither a listed impairment nor its equivalent, is nevertheless of “comparable severity” and hence disabling when considered with nonmedical factors.

I thus largely agree with District Judge Fullam’s view of this case:

“Plaintiff’s argument may well be valid, in many cases; but errors in applying the regulations in some cases do not demonstrate invalidity of the regulations themselves. Part B of the Secretary’s listings of impairments, 20 CFR §416.925, is not facially invalid or incom-*546píete, seems to provide the necessary flexibility, and, in my view, permits the award of benefits in conformity with the intent of Congress. If these criteria are being misapplied or misinterpreted, the remedy lies in the appeal process in individual cases, not in a class-action decree.” Zebley v. Heckler, 642 F. Supp. 220, 222 (ED Pa. 1986).

The difference, furthermore, between the Secretary’s regulatory approach toward adults and his approach toward children accords with the different purposes underlying the disability programs for the two groups. Congress provided disability benefits for adults in order to ensure “the basic means of replacing earnings that have been lost as a result of . . . disability” for those who “are not able to support themselves through work . . . .” H. R. Rep. No. 92-231, pp. 146-147 (1971). For this reason, insofar as adults are concerned, the Act defines disabilities in terms of the effect that the disabilities have on the claimant’s ability to function in the workplace. In light of this purpose, it is appropriate for the Secretary to evaluate adults not only in terms of the severity of their impairment, but also in terms of their residual functional capacity to perform work.

By contrast, Congress had a different set of considerations in mind when it provided for children’s benefits. Recognizing that disabled children from low-income households are “among the most disadvantaged of all Americans,” Congress provided special disability benefits for these persons “because their needs are often greater than those of nondisabled children.” H. R. Rep. No. 92-231, supra, at 147-148. In other words, Congress’ aim in providing benefits to these individuals was not to replace lost income, but rather to provide for their special health care expenses, such as the home health care costs arising out of the child’s medical disability. It is consistent with this quite distinct púrpose to focus consideration on the severity of the child’s impairment from a medical perspective alone, without individualized consider*547ation of vocational or similar factors or the claimant’s residual functional capacity. The nature and severity of a child’s impairment, rather than the child’s ability to contribute to his family’s income, will necessarily determine the child’s entitlement to benefits.2

I also note that the majority faults the regulations on the grounds that they do not adequately provide for considering multiple impairments together. Ante, at 534. As 42 U. S. C. § 1382c(a)(3)(F) (1982 ed., Supp. IV) requires, however, the regulations expressly provide that impairments in combination may add up to qualify for benefits. 20 CFR §416.923 (1989). The Court of Appeals recognized that the Secretary’s regulations faithfully implement the statutory mandate “by providing generally that the combined effect of all of a claimant’s impairments will be considered throughout the disability determination process.” Zebley v. Bowen, 855 F. 2d 67, 76 (CA3 1988). There is no cross-petition challenging this aspect of the judgment below, and the Court should therefore not expand the relief obtained in the Court of Appeals.

In sum, because I cannot conclude that the Secretary’s method for evaluating child-disability claims is an impermis*548sible construction of the Act, I dissent. The Social Security Administration processes over 100,000 child-disability claims a year. The agency has a finite amount of funds with which to work. By requiring the Secretary to conduct unspecified individualized determinations in cases where an applicant fails to satisfy the agency that he is otherwise disabled, the majority imposes costs on the agency that surely will detract from the pool of benefits available to the unfortunate children that Congress has sought to protect through the Supplemental Security Income Program.