(Slip Opinion)              OCTOBER TERM, 2011                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

  ASTRUE, COMMISSIONER OF SOCIAL SECURITY v. 

       CAPATO, ON BEHALF OF B. N. C. ET AL. 


CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                  THE THIRD CIRCUIT

      No. 11–159.      Argued March 19, 2012—Decided May 21, 2012
Eighteen months after her husband, Robert Capato, died of cancer, re-
  spondent Karen Capato gave birth to twins conceived through in
  vitro fertilization using her husband’s frozen sperm. Karen applied
  for Social Security survivors benefits for the twins. The Social Secu-
  rity Administration (SSA) denied her application, and the District
  Court affirmed. In accord with the SSA’s construction of the Social
  Security Act (Act), the court determined that the twins would qualify
  for benefits only if, as 42 U. S. C. §416(h)(2)(A) specifies, they could
  inherit from the deceased wage earner under state intestacy law.
  The court then found that Robert was domiciled in Florida at his
  death, and that under Florida law, posthumously conceived children
  do not qualify for inheritance through intestate succession. The
  Third Circuit reversed. It concluded that, under §416(e), which de-
  fines child to mean, inter alia, “the child or legally adopted child of an
  [insured] individual,” the undisputed biological children of an insured
  and his widow qualify for survivors benefits without regard to state
  intestacy law.
Held: The SSA’s reading is better attuned to the statute’s text and its
 design to benefit primarily those supported by the deceased wage
 earner in his or her lifetime. Moreover, even if the SSA’s longstand-
 ing interpretation is not the only reasonable one, it is at least a per-
 missible construction entitled to deference under Chevron U. S. A.
 Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837. Pp. 4–
 16.
    (a) Congress amended the Act in 1939 to provide that, as relevant
 here, “[e]very child (as defined in section 416(e) of this title)” of a de-
2                           ASTRUE v. CAPATO

                                  Syllabus

    ceased insured individual “shall be entitled to a child’s insurance
    benefit.” §402(d). Section 416(e), in turn, defines “child” to mean:
    “(1) the child or legally adopted child of an individual, (2) a stepchild
    [under certain circumstances], and (3) . . . the grandchild or
    stepgrandchild of an individual or his spouse [under certain condi-
    tions].” Unlike §§416(e)(2) and (3), §416(e)(1) lacks any elaboration of
    the conditions under which a child qualifies for benefits. Section
    416(h)(2)(A), however, further addresses the term “child,” providing:
    “In determining whether an applicant is the child or parent of [an]
    insured individual for purposes of this subchapter, the Commissioner
    of Social Security shall apply [the intestacy law of the insured indi-
    vidual’s domiciliary State].” An applicant who does not meet
    §416(h)(2)(A)’s intestacy-law criterion may nonetheless qualify for
    benefits under other criteria set forth in §§416(h)(2)(B) and (h)(3), but
    respondent does not claim eligibility under those other criteria. Reg-
    ulations promulgated by the SSA closely track §§416(h)(2) and (3) in
    defining “[w]ho is the insured’s natural child,” 20 CFR §404.355. As
    the SSA reads the statute, 42 U. S. C. §416(h) governs the meaning of
    “child” in §416(e)(1) and serves as a gateway through which all appli-
    cants for insurance benefits as a “child” must pass. Pp. 4–7.
       (b) While the SSA regards §416(h) as completing §416(e)’s sparse
    definition of “child,” the Third Circuit held, and respondent contends,
    that §416(e) alone governs whenever the claimant is a married cou-
    ple’s biological child. There are conspicuous flaws in the Third Cir-
    cuit’s and respondent’s reading; the SSA offers the more persuasive
    interpretation. Pp. 7–15.
         (1) Nothing in §416(e)’s tautological definition suggests that
    Congress understood the word “child” to refer only to the children of
    married parents. The dictionary definitions offered by respondent
    are not so confined. Moreover, elsewhere in the Act, Congress ex-
    pressly limited the category of children covered to offspring of a mari-
    tal union, see §402(d)(3)(A), and contemporaneous statutes similarly
    distinguish child of a marriage from the unmodified term “child.”
    Nor does §416(e) indicate that Congress intended “biological” parent-
    age to be prerequisite to “child” status. A biological parent is not al-
    ways a child’s parent under law. Furthermore, marriage does not
    necessarily make a child’s parentage certain, nor does the absence of
    marriage necessarily make a child’s parentage uncertain. Finally, it
    is far from obvious that respondent’s proposed definition would cover
    her posthumously conceived twins, for under Florida law a marriage
    ends upon the death of a spouse. Pp. 8–10.
         (2) The SSA finds a key textual cue in §416(h)(2)(A)’s opening in-
    struction: “In determining whether an applicant is the child . . . of
    [an] insured individual for purposes of this subchapter,” the Commis-
                   Cite as: 566 U. S. ____ (2012)                     3

                              Syllabus

sioner shall apply state intestacy law. Respondent notes the absence
of any cross-reference in §416(e) to §416(h), but she overlooks that
§416(h) provides the crucial link: It requires reference to state intes-
tacy law to determine child status not just for §416(h) purposes, but
“for purposes of this subchapter,” which includes both §§402(d) and
416(e). Having explicitly complemented §416(e) by the definitional
provisions contained in §416(h), Congress had no need to place a re-
dundant cross-reference in §416(e).
   The Act commonly refers to state law on matters of family status,
including an applicant’s status as a wife, widow, husband, or widow-
er. See, e.g., §§416(b), (h)(1)(A). The Act also sets duration-of-
relationship limitations, see Weinberger v. Salfi, 422 U. S. 749, 777–
782, and time limits qualify the statutes of several States that accord
inheritance rights to posthumously conceived children. In contrast,
no time constraint attends the Third Circuit’s ruling in this case, un-
der which the biological child of married parents is eligible for survi-
vors benefits, no matter the length of time between the father’s death
and the child’s conception and birth.
   Because a child who may take from a father’s estate is more likely
to “be dependent during the parent’s life and at his death,” Mathews
v. Lucas, 427 U. S. 495, 514, reliance on state intestacy law to deter-
mine who is a “child” serves the Act’s driving objective, which is to
“provide . . . dependent members of [a wage earner’s] family with pro-
tection against the hardship occasioned by [the] loss of [the insured’s]
earnings,” Califano v. Jobst, 434 U. S. 47, 52. Although the Act and
regulations set different eligibility requirements for adopted children,
stepchildren, grandchildren, and stepgrandchildren, it hardly follows,
as respondent argues, that applicants in those categories are treated
more advantageously than are children who must meet a §416(h) cri-
terion. Respondent charges that the SSA’s construction of the Act
raises serious constitutional concerns under the equal protection
component of the Due Process Clause. But under rational-basis re-
view, the appropriate standard here, the regime passed by Congress
easily passes inspection. Pp. 10–15.
   (c) Because the SSA’s interpretation of the relevant provisions, is
at least reasonable, the agency’s reading is entitled to this Court’s
deference under Chevron, 467 U. S. 837. Chevron deference is appro-
priate “when it appears that Congress delegated authority to the
agency generally to make rules carrying the force of law, and that the
agency interpretation claiming deference was promulgated in the ex-
ercise of that authority.” United States v. Mead Corp., 533 U. S. 218,
226–227. Here, the SSA’s longstanding interpretation, set forth in
regulations published after notice-and-comment rulemaking, is nei-
ther “arbitrary or capricious in substance, [n]or manifestly contrary
4                         ASTRUE v. CAPATO

                                 Syllabus

    to the statute.” Mayo Foundation for Medical Ed. and Research v.
    United States, 562 U. S. ___, ___. It therefore warrants the Court’s
    approbation. Pp. 15–16.
631 F. 3d 626, reversed and remanded.

    GINSBURG, J., delivered the opinion for a unanimous Court.
                        Cite as: 566 U. S. ____ (2012)                              1

                             Opinion of the Court

     NOTICE: This opinion is subject to formal revision before publication in the
     preliminary print of the United States Reports. Readers are requested to
     notify the Reporter of Decisions, Supreme Court of the United States, Wash-
     ington, D. C. 20543, of any typographical or other formal errors, in order
     that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                   _________________

                                   No. 11–159
                                   _________________


 MICHAEL J. ASTRUE, COMMISSIONER OF SOCIAL

  SECURITY, PETITIONER v. KAREN K. CAPATO, 

          ON BEHALF OF B. N. C., ET AL. 


 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF

            APPEALS FOR THE THIRD CIRCUIT

                                 [May 21, 2012]


  JUSTICE GINSBURG delivered the opinion of the Court.
  Karen and Robert Capato married in 1999. Robert died
of cancer less than three years later. With the help of in
vitro fertilization, Karen gave birth to twins 18 months
after her husband’s death. Karen’s application for Social
Security survivors benefits for the twins, which the Social
Security Administration (SSA) denied, prompted this lit-
igation. The technology that made the twins’ conception
and birth possible, it is safe to say, was not contemplated
by Congress when the relevant provisions of the Social
Security Act (Act) originated (1939) or were amended to
read as they now do (1965).
  Karen Capato, respondent here, relies on the Act’s
initial definition of “child” in 42 U. S. C. §416(e): “ ‘[C]hild’
means . . . the child or legally adopted child of an [insured]
individual.” Robert was an insured individual, and the
twins, it is uncontested, are the biological children of
Karen and Robert. That satisfies the Act’s terms, and no
further inquiry is in order, Karen maintains. The SSA,
however, identifies subsequent provisions, §§416(h)(2) and
2                    ASTRUE v. CAPATO

                     Opinion of the Court

(h)(3)(C), as critical, and reads them to entitle biological
children to benefits only if they qualify for inheritance
from the decedent under state intestacy law, or satisfy one
of the statutory alternatives to that requirement.
   We conclude that the SSA’s reading is better attuned to
the statute’s text and its design to benefit primarily those
supported by the deceased wage earner in his or her life-
time. And even if the SSA’s longstanding interpretation is
not the only reasonable one, it is at least a permissible
construction that garners the Court’s respect under Chev-
ron U. S. A. Inc. v. Natural Resources Defense Council,
Inc., 467 U. S. 837 (1984).
                              I
   Karen Capato married Robert Capato in May 1999.
Shortly thereafter, Robert was diagnosed with esophageal
cancer and was told that the chemotherapy he required
might render him sterile. Because the couple wanted
children, Robert, before undergoing chemotherapy, depos-
ited his semen in a sperm bank, where it was frozen and
stored. Despite Robert’s aggressive treatment regime,
Karen conceived naturally and gave birth to a son in
August 2001. The Capatos, however, wanted their son to
have a sibling.
   Robert’s health deteriorated in late 2001, and he died in
Florida, where he and Karen then resided, in March 2002.
His will, executed in Florida, named as beneficiaries the
son born of his marriage to Karen and two children from
a previous marriage. The will made no provision for chil-
dren conceived after Robert’s death, although the Capatos
had told their lawyer they wanted future offspring to be
placed on a par with existing children. Shortly after Rob-
ert’s death, Karen began in vitro fertilization using her
husband’s frozen sperm. She conceived in January 2003
and gave birth to twins in September 2003, 18 months
after Robert’s death.
                      Cite as: 566 U. S. ____ (2012)                      3

                           Opinion of the Court

  Karen Capato claimed survivors insurance benefits on
behalf of the twins. The SSA denied her application, and
the U. S. District Court for the District of New Jersey
affirmed the agency’s decision. See App. to Pet. for Cert.
33a (decision of the Administrative Law Judge); id., at
15a (District Court opinion). In accord with the SSA’s
construction of the statute, the District Court determined
that the twins would qualify for benefits only if, as
§416(h)(2)(A) specifies, they could inherit from the de-
ceased wage earner under state intestacy law. Robert
Capato died domiciled in Florida, the court found. Under
that State’s law, the court noted, a child born posthu-
mously may inherit through intestate succession only if
conceived during the decedent’s lifetime. Id., at 27a–28a.1
  The Court of Appeals for the Third Circuit reversed.
Under §416(e), the appellate court concluded, “the undis-
puted biological children of a deceased wage earner and
his widow” qualify for survivors benefits without regard to
state intestacy law. 631 F. 3d 626, 631 (2011).2 Courts of
Appeals have divided on the statutory interpretation
question this case presents. Compare ibid. and Gillett-
Netting v. Barnhart, 371 F. 3d 593, 596–597 (CA9 2004)
(biological but posthumously conceived child of insured
wage earner and his widow qualifies for benefits), with
Beeler v. Astrue, 651 F. 3d 954, 960–964 (CA8 2011), and
——————
  1 The District Court observed that Fla. Stat. Ann. §732.106 (West

2010) defines “ ‘afterborn heirs’ ” as “ ‘heirs of the decedent conceived
before his or her death, but born thereafter.’ ” App. to Pet. for Cert.
27a (emphasis added by District Court). The court also referred to
§742.17(4), which provides that a posthumously conceived child “ ‘shall
not be eligible for a claim against the decedent’s estate unless the child
has been provided for by the decedent’s will.’ ” Id., at 28a.
  2 Because the Third Circuit held that posthumously conceived chil-

dren qualify for survivors benefits as a matter of federal law, it did not
definitively determine “where [Robert] Capato was domiciled at his
death or . . . delve into the law of intestacy of that state.” 631 F. 3d, at
632, n. 6. These issues, if preserved, may be considered on remand.
4                        ASTRUE v. CAPATO

                         Opinion of the Court

Schafer v. Astrue, 641 F. 3d 49, 54–63 (CA4 2011) (post-
humously conceived child’s qualification for benefits de-
pends on intestacy law of State in which wage earner was
domiciled). To resolve the conflict, we granted the Com-
missioner’s petition for a writ of certiorari. 565 U. S. ___
(2011).
                               II
   Congress amended the Social Security Act in 1939 to
provide a monthly benefit for designated surviving fam-
ily members of a deceased insured wage earner. “Child’s
insurance benefits” are among the Act’s family-protective
measures. 53 Stat. 1364, as amended, 42 U. S. C. §402(d).
An applicant qualifies for such benefits if she meets the
Act’s definition of “child,” is unmarried, is below specified
age limits (18 or 19) or is under a disability which began
prior to age 22, and was dependent on the insured at the
time of the insured’s death. §402(d)(1).3
   To resolve this case, we must decide whether the Capato
twins rank as “child[ren]” under the Act’s definitional
provisions. Section 402(d) provides that “[e]very child (as
defined in section 416(e) of this title)” of a deceased in-
sured individual “shall be entitled to a child’s insurance
benefit.” Section 416(e), in turn, states: “The term ‘child’
means (1) the child or legally adopted child of an individ-
——————
  3 Applicants not in fact dependent on the insured individual may be

“deemed dependent” when the Act so provides. For example, a “legiti-
mate” child, even if she is not living with or receiving support from
her parent, is ordinarily “deemed dependent” on that parent. 42 U. S. C.
§402(d)(3). Further, applicants “deemed” the child of an insured
individual under §416(h)(2)(B) or (h)(3) are also “deemed legitimate,”
hence dependent, even if not living with or receiving support from
the parent. §402(d)(3). See also Mathews v. Lucas, 427 U. S. 495, 499,
n. 2 (1976) (deeming dependent any child who qualifies under
§416(h)(2)(A)); Tr. of Oral Arg. 13–14 (counsel for the SSA stated, in
response to the Court’s question, that statutory presumptions of de-
pendency are irrebuttable).
                     Cite as: 566 U. S. ____ (2012)                   5

                         Opinion of the Court

ual, (2) a stepchild [under certain circumstances], and (3)
. . . the grandchild or stepgrandchild of an individual or
his spouse [who meets certain conditions].”
    The word “child,” we note, appears twice in §416(e)’s
opening sentence: initially in the prefatory phrase, “[t]he
term ‘child’ means . . . ,” and, immediately thereafter, in
subsection (e)(1) (“child or legally adopted child”), deline-
ating the first of three beneficiary categories. Unlike
§§416(e)(2) and (3), which specify the circumstances under
which stepchildren and grandchildren qualify for benefits,
§416(e)(1) lacks any elaboration. Compare §416(e)(1)
(referring simply to “the child . . . of an individual”) with,
e.g., §416(e)(2) (applicant must have been a stepchild for at
least nine months before the insured individual’s death).
    A subsequent definitional provision further addresses
the term “child.” Under the heading “Determination of
family status,” §416(h)(2)(A) provides: “In determining
whether an applicant is the child or parent of [an] insured
individual for purposes of this subchapter, the Commis-
sioner of Social Security shall apply [the intestacy law of
the insured individual’s domiciliary State].”4
    An applicant for child benefits who does not meet
§416(h)(2)(A)’s intestacy-law criterion may nonetheless
qualify for benefits under one of several other criteria the
Act prescribes. First, an applicant who “is a son or daugh-
ter” of an insured individual, but is not determined to be a
“child” under the intestacy-law provision, nevertheless

——————
  4 Section 416(h)(2)(A) also states that persons who, under the law of

the insured’s domicile, “would have the same status relative to taking
intestate personal property as a child or parent shall be deemed such.”
Asked about this prescription, counsel for the SSA responded that it
would apply to equitably adopted children. Tr. of Oral Arg. 8–9, 54; see
20 CFR §404.359 (2011) (an equitably adopted child may be eligible for
benefits if the agreement to adopt the child would be recognized under
state law as enabling the child to inherit upon the intestate death of
the adopting parent).
6                        ASTRUE v. CAPATO

                          Opinion of the Court

ranks as a “child” if the insured and the other parent went
through a marriage ceremony that would have been valid
but for certain legal impediments. §416(h)(2)(B). Further,
an applicant is deemed a “child” if, before death, the in-
sured acknowledged in writing that the applicant is his or
her son or daughter, or if the insured had been decreed by
a court to be the father or mother of the applicant, or had
been ordered to pay child support. §416(h)(3)(C)(i). In
addition, an applicant may gain “child” status upon
proof that the insured individual was the applicant’s pa-
rent and “was living with or contributing to the support
of the applicant” when the insured individual died.
§416(h)(3)(C)(ii).5
  The SSA has interpreted these provisions in regulations
adopted through notice-and-comment rulemaking. The
regulations state that an applicant may be entitled to
benefits “as a natural child, legally adopted child, step-
child, grandchild, stepgrandchild, or equitably adopted
child.” 20 CFR §404.354. Defining “[w]ho is the insured’s
natural child,” §404.355, the regulations closely track
42 U. S. C. §§416(h)(2) and (h)(3). They state that an
applicant may qualify for insurance benefits as a “natural
child” by meeting any of four conditions: (1) the applicant
“could inherit the insured’s personal property as his or her
natural child under State inheritance laws”; (2) the appli-
cant is “the insured’s natural child and [his or her parents]
went through a ceremony which would have resulted in
a valid marriage between them except for a legal impedi-
ment”; (3) before death, the insured acknowledged in
writing his or her parentage of the applicant, was decreed
by a court to be the applicant’s parent, or was ordered by a
court to contribute to the applicant’s support; or (4) other
evidence shows that the insured is the applicant’s “natural
——————
  5 Respondent does not invoke any of the alternative criteria as a basis

for the twins’ “child” status.
                      Cite as: 566 U. S. ____ (2012)                     7

                          Opinion of the Court

father or mother” and was either living with, or contrib-
uting to the support of, the applicant. 20 CFR §404.355(a)
(internal quotation marks omitted).
   As the SSA reads the statute, 42 U. S. C. §416(h) gov-
erns the meaning of “child” in §416(e)(1). In other words,
§416(h) is a gateway through which all applicants for in-
surance benefits as a “child” must pass. See Beeler, 651
F. 3d, at 960 (“The regulations make clear that the SSA
interprets the Act to mean that the provisions of §416(h)
are the exclusive means by which an applicant can estab-
lish ‘child’ status under §416(e) as a natural child.”).6
                               III
  Karen Capato argues, and the Third Circuit held, that
§416(h), far from supplying the governing law, is irrele-
vant in this case. Instead, the Court of Appeals deter-
mined, §416(e) alone is dispositive of the controversy. 631
F. 3d, at 630–631. Under §416(e), “child” means “child of
an [insured] individual,” and the Capato twins, the Third
Circuit observed, clearly fit that definition: They are un-
deniably the children of Robert Capato, the insured wage
earner, and his widow, Karen Capato. Section 416(h)
comes into play, the court reasoned, only when “a claim-
ant’s status as a deceased wage-earner’s child is in doubt.”
Id., at 631. That limitation, the court suggested, is evi-
dent from §416(h)’s caption: “Determination of family
status.” Here, “there is no family status to determine,” the
court said, id., at 630, so §416(h) has no role to play.
  In short, while the SSA regards §416(h) as completing
§416(e)’s sparse definition of “child,” the Third Circuit
considered each subsection to control different situations:
§416(h) governs when a child’s family status needs to be
determined; §416(e), when it does not. When is there no
——————
  6 The Commissioner of Social Security has acquiesced in the Ninth

Circuit’s conflicting interpretation for cases arising in that Circuit. See
Social Security Acquiescence Ruling 05–1(9), 70 Fed. Reg. 55656 (2005).
8                        ASTRUE v. CAPATO

                         Opinion of the Court

need to determine a child’s family status? The answer
that the Third Circuit found plain: whenever the claimant
is “the biological child of a married couple.” Id., at 630.7
   We point out, first, some conspicuous flaws in the Third
Circuit’s and respondent Karen Capato’s reading of the
Act’s provisions, and then explain why we find the SSA’s
interpretation persuasive.
                               A
  Nothing in §416(e)’s tautological definition (“ ‘child’
means . . . the child . . . of an individual”) suggests that
Congress understood the word “child” to refer only to the
children of married parents. The dictionary definitions
offered by respondent are not so confined. See Webster’s
New International Dictionary 465 (2d ed. 1934) (defining
“child” as, inter alia, “[i]n Law, legitimate offspring; also,
sometimes, esp. in wills, an adopted child, or an illegiti-
mate offspring, or any direct descendant, as a grandchild,
as the intention may appear”); Merriam-Webster’s Colle-
giate Dictionary 214 (11th ed. 2003) (“child” means “son or
daughter,” or “descendant”). See also Restatement (Third)
of Property §2.5(1) (1998) (“[a]n individual is the child of
his or her genetic parents,” and that may be so “whether
or not [the parents] are married to each other”). More-
over, elsewhere in the Act, Congress expressly limited
the category of children covered to offspring of a marital
union. See §402(d)(3)(A) (referring to the “legitimate . . .
child” of an individual). Other contemporaneous statutes
similarly differentiate child of a marriage (“legitimate
child”) from the unmodified term “child.” See, e.g., Ser-
vicemen’s Dependents Allowance Act of 1942, ch. 443,
——————
  7 Because the Court of Appeals found the statutory language unam-

biguous, it had no occasion to “determine whether the [SSA’s] interpre-
tation is a permissible construction of the statute.” 631 F. 3d, at 631,
n. 5 (citing Chevron U. S. A. Inc. v. Natural Resources Defense Council,
Inc., 467 U. S. 837, 842–843 (1984)).
                 Cite as: 566 U. S. ____ (2012)            9

                     Opinion of the Court

§120, 56 Stat. 385 (defining “child” to include “legitimate
child,” “child legally adopted,” and, under certain condi-
tions, “stepchild” and “illegitimate child” (internal quota-
tion marks omitted)).
   Nor does §416(e) indicate that Congress intended “bio-
logical” parentage to be prerequisite to “child” status
under that provision. As the SSA points out, “[i]n 1939,
there was no such thing as a scientifically proven biologi-
cal relationship between a child and a father, which is . . .
part of the reason that the word ‘biological’ appears no-
where in the Act.” Reply Brief 6. Notably, a biological
parent is not necessarily a child’s parent under law.
Ordinarily, “a parent-child relationship does not exist
between an adoptee and the adoptee’s genetic parents.”
Uniform Probate Code §2–119(a), 8 U. L. A. 55 (Supp.
2011) (amended 2008). Moreover, laws directly addressing
use of today’s assisted reproduction technology do not
make biological parentage a universally determinative
criterion. See, e.g., Cal. Fam. Code Ann. §7613(b) (West
Supp. 2012) (“The donor of semen . . . for use in artificial
insemination or in vitro fertilization of a woman other
than the donor’s wife is treated in law as if he were not the
natural father of a child thereby conceived, unless other-
wise agreed to in a writing signed by the donor and the
woman prior to the conception of the child.”); Mass. Gen.
Laws, ch. 46, §4B (West 2010) (“Any child born to a mar-
ried woman as a result of artificial insemination with the
consent of her husband, shall be considered the legitimate
child of the mother and such husband.”).
   We note, in addition, that marriage does not ever and
always make the parentage of a child certain, nor does the
absence of marriage necessarily mean that a child’s par-
entage is uncertain. An unmarried couple can agree that
a child is theirs, while the parentage of a child born during
a marriage may be uncertain. See Reply Brief 11 (“Re-
spondent errs in treating ‘marital’ and ‘undisputed’ as
10                      ASTRUE v. CAPATO

                        Opinion of the Court

having the same meaning.”).
  Finally, it is far from obvious that Karen Capato’s pro-
posed definition—“biological child of married parents,” see
Brief for Respondent 9—would cover the posthumously
conceived Capato twins. Under Florida law, a marriage
ends upon the death of a spouse. See Price v. Price, 114
Fla. 233, 235, 153 So. 904, 905 (1934). If that law applies,
rather than a court-declared preemptive federal law, the
Capato twins, conceived after the death of their father,
would not qualify as “marital” children.8
                            B
   Resisting the importation of words not found in
§416(e)—“child” means “the biological child of married
parents,” Brief for Respondent 9—the SSA finds a key
textual cue in §416(h)(2)(A)’s opening instruction: “In
determining whether an applicant is the child . . . of [an]
insured individual for purposes of this subchapter,” the
Commissioner shall apply state intestacy law. (Emphasis
added.) Respondent notes the absence of any cross-
reference in §416(e) to §416(h). Brief for Respondent 18.
She overlooks, however, that §416(h) provides the crucial
link. The “subchapter” to which §416(h) refers is Sub-
chapter II of the Act, which spans §§401 through 434.
Section 416(h)’s reference to “this subchapter” thus in-
cludes both §§402(d) and 416(e). Having explicitly com-
plemented §416(e) by the definitional provisions contained
in §416(h), Congress had no need to place a redundant
cross-reference in §416(e). See Schafer, 641 F. 3d, at 54
——————
  8 Respondent urges that it would be bizarre to deny benefits to the

Capato twins when, under §416(h)(2)(B), they would have gained
benefits had their parents gone through a marriage ceremony that
would have been valid save for a legal impediment. Brief for Respond-
ent 26, n. 10; see supra, at 5–6. Whether the Capatos’ marriage cere-
mony was flawed or flawless, the SSA counters, no marital union was
extant when the twins were conceived. Reply Brief 11.
                   Cite as: 566 U. S. ____ (2012)             11

                       Opinion of the Court

(Congress, in §416(h)(2)(A), provided “plain and explicit
instruction on how the determination of child status
should be made”; on this point, the statute’s text “could
hardly be more clear.”).
   The original version of today’s §416(h) was similarly
drafted. It provided that, “[i]n determining whether an
applicant is the . . . child . . . of [an] insured individual for
purposes of sections 401–409 of this title, the Board shall
apply [state intestacy law].” 42 U. S. C. §409(m) (1940 ed.)
(emphasis added). Sections 401–409 embraced §§402(c)
and 409(k), the statutory predecessors of 42 U. S. C.
§§402(d) and 416(e) (2006 ed.), respectively.
   Reference to state law to determine an applicant’s sta-
tus as a “child” is anything but anomalous. Quite the
opposite. The Act commonly refers to state law on matters
of family status. For example, the Act initially defines
“wife” as “the wife of an [insured] individual,” if certain
conditions are satisfied. §416(b). Like §416(e), §416(b)
is, at least in part, tautological (“ ‘wife’ means the [in-
sured’s] wife”). One must read on, although there is no ex-
press cross-reference, to §416(h) (rules on “[d]etermination
of family status”) to complete the definition. Section
§416(h)(1)(A) directs that, “for purposes of this subchap-
ter,” the law of the insured’s domicile determines whether
“[the] applicant and [the] insured individual were validly
married,” and if they were not, whether the applicant
would nevertheless have “the same status” as a wife under
the State’s intestacy law. (Emphasis added.) The Act
similarly defines the terms “widow,” “husband,” and “wid-
ower.” See §§416(c), (f), (g), (h)(1)(A).
   Indeed, as originally enacted, a single provision man-
dated the use of state intestacy law for “determining
whether an applicant is the wife, widow, child, or parent of
[an] insured individual.” 42 U. S. C. §409(m) (1940 ed.).
All wife, widow, child, and parent applicants thus had to
satisfy the same criterion. To be sure, children born dur-
12                   ASTRUE v. CAPATO

                     Opinion of the Court

ing their parents’ marriage would have readily qualified
under the 1939 formulation because of their eligibility
to inherit under state law. But requiring all “child” ap-
plicants to qualify under state intestacy law installed a
simple test, one that ensured benefits for persons plainly
within the legislators’ contemplation, while avoiding con-
gressional entanglement in the traditional state-law
realm of family relations.
   Just as the Act generally refers to state law to deter-
mine whether an applicant qualifies as a wife, widow,
husband, widower, 42 U. S. C. §416(h)(1) (2006 ed.), child
or parent, §416(h)(2)(A), so in several sections (§§416(b),
(c), (e)(2), (f), (g)), the Act sets duration-of-relationship
limitations. See Weinberger v. Salfi, 422 U. S. 749, 777–
782 (1975) (discussing §416(e)(2)’s requirement that, as
a check against deathbed marriages, a parent-stepchild
relationship must exist “not less than nine months imme-
diately preceding [insured’s death]”). Time limits also
qualify the statutes of several States that accord inher-
itance rights to posthumously conceived children. See Cal.
Prob. Code Ann. §249.5(c) (West Supp. 2012) (allowing
inheritance if child is in utero within two years of parent’s
death); Colo. Rev. Stat. Ann. §15–11–120(11) (2011) (child
in utero within three years or born within 45 months);
Iowa Code Ann. §633.220A(1) (West Supp. 2012) (child
born within two years); La. Rev. Stat. Ann. §9:391.1(A)
(West 2008) (child born within three years); N. D. Cent.
Code Ann. §30.1–04–19(11) (Lexis 2001) (child in utero
within three years or born within 45 months). See also
Uniform Probate Code §2–120(k), 8 U. L. A. 58 (Supp.
2011) (treating a posthumously conceived child as “in
gestation at the individual’s death,” but only if specified
time limits are met). No time constraints attend the Third
Circuit’s ruling in this case, under which the biological
child of married parents is eligible for survivors benefits,
no matter the length of time between the father’s death
                      Cite as: 566 U. S. ____ (2012)                    13

                          Opinion of the Court

and the child’s conception and birth. See Tr. of Oral Arg.
36–37 (counsel for Karen Capato acknowledged that,
under the preemptive federal rule he advocated, and the
Third Circuit adopted, a child born four years after her
father’s death would be eligible for benefits).
   The paths to receipt of benefits laid out in the Act and
regulations, we must not forget, proceed from Congress’
perception of the core purpose of the legislation. The aim
was not to create a program “generally benefiting needy
persons”; it was, more particularly, to “provide . . . de-
pendent members of [a wage earner’s] family with protec-
tion against the hardship occasioned by [the] loss of [the
insured’s] earnings.” Califano v. Jobst, 434 U. S. 47, 52
(1977). We have recognized that “where state intestacy
law provides that a child may take personal property from
a father’s estate, it may reasonably be thought that the
child will more likely be dependent during the parent’s life
and at his death.” Mathews v. Lucas, 427 U. S. 495, 514
(1976). Reliance on state intestacy law to determine who
is a “child” thus serves the Act’s driving objective. True,
the intestacy criterion yields benefits to some children
outside the Act’s central concern. Intestacy laws in a
number of States, as just noted, do provide for inheritance
by posthumously conceived children, see supra, at 12,9 and
under federal law, a child conceived shortly before her
father’s death may be eligible for benefits even though she
never actually received her father’s support. It was none-
theless Congress’ prerogative to legislate for the generality
of cases. It did so here by employing eligibility to inherit
——————
   9 But see N. Y. Est., Powers & Trusts Law Ann. §4–1.1(c) (West 1998)

(“Distributees of the decedent, conceived before his or her death but
born alive thereafter, take as if they were born in his or her lifetime.”).
Similar provisions are contained in Ga. Code Ann. §53–2–1(b)(1) (2011),
Idaho Code §15–2–108 (Lexis 2009), Minn. Stat. Ann. §524.2–120(10)
(West Supp. 2012), S. C. Code Ann. §62–2–108 (2009), and S. D. Codi-
fied Laws §29A–2–108 (Supp. 2011).
14                   ASTRUE v. CAPATO

                     Opinion of the Court

under state intestacy law as a workable substitute for bur-
densome case-by-case determinations whether the child
was, in fact, dependent on her father’s earnings.
   Respondent argues that on the SSA’s reading, natural
children alone must pass through a §416(h) gateway.
Adopted children, stepchildren, grandchildren, and step-
grandchildren, it is true, are defined in §416(e), and are
not further defined in §416(h). Respondent overlooks,
however, that although not touched by §416(h), beneficiar-
ies described in §§416(e)(2) and (e)(3) must meet other
statutorily prescribed criteria. In short, the Act and regu-
lations set different eligibility requirements for adopted
children, stepchildren, grandchildren, and stepgrandchil-
dren, see 20 CFR §§404.356–404.358, but it hardly follows
that applicants in those categories are treated more ad-
vantageously than are children who must meet a §416(h)
criterion.
   The SSA’s construction of the Act, respondent charges,
raises serious constitutional concerns under the equal pro-
tection component of the Due Process Clause. Brief for
Respondent 42; see Weinberger v. Wiesenfeld, 420 U. S.
636, 638, n. 2 (1975). She alleges: “Under the govern-
ment’s interpretation . . . , posthumously conceived chil-
dren are treated as an inferior subset of natural children
who are ineligible for government benefits simply because
of their date of birth and method of conception.” Brief for
Respondent 42–43.
   Even the Courts of Appeals that have accepted the
reading of the Act respondent advances have rejected this
argument. See 631 F. 3d, at 628, n. 1 (citing Vernoff
v. Astrue, 568 F. 3d 1102, 1112 (CA9 2009)). We have
applied an intermediate level of scrutiny to laws “bur-
den[ing] illegitimate children for the sake of punishing the
illicit relations of their parents, because ‘visiting this
condemnation on the head of an infant is illogical and
unjust.’ ” Clark v. Jeter, 486 U. S. 456, 461 (1988) (quoting
                     Cite as: 566 U. S. ____ (2012)                  15

                         Opinion of the Court

Weber v. Aetna Casualty & Surety Co., 406 U. S. 164, 175
(1972)). No showing has been made that posthumously
conceived children share the characteristics that prompted
our skepticism of classifications disadvantaging children
of unwed parents. We therefore need not decide whether
heightened scrutiny would be appropriate were that the
case.10 Under rational-basis review, the regime Congress
adopted easily passes inspection. As the Ninth Circuit
held, that regime is “reasonably related to the govern-
ment’s twin interests in [reserving] benefits [for] those
children who have lost a parent’s support, and in using
reasonable presumptions to minimize the administrative
burden of proving dependency on a case-by-case basis.”
Vernoff, 568 F. 3d, at 1112 (citing Mathews, 427 U. S., at
509).
                              IV
  As we have explained, §416(e)(1)’s statement, “[t]he
term ‘child’ means . . . the child . . . of an individual,” is a
definition of scant utility without aid from neighboring
provisions. See Schafer, 641 F. 3d, at 54. That aid is
supplied by §416(h)(2)(A), which completes the definition
of “child” “for purposes of th[e] subchapter” that includes
§416(e)(1). Under the completed definition, which the SSA
employs, §416(h)(2)(A) refers to state law to determine the
status of a posthumously conceived child. The SSA’s
interpretation of the relevant provisions, adhered to with-
out deviation for many decades, is at least reasonable; the
agency’s reading is therefore entitled to this Court’s defer-
——————
  10 Ironically, while drawing an analogy to the “illogical and unjust”

discrimination children born out of wedlock encounter, see Weber v.
Aetna Casualty & Surety Co., 406 U. S. 164, 175–176 (1972), respond-
ent asks us to differentiate between children whose parents were
married and children whose parents’ liaisons were not blessed by clergy
or the State. She would eliminate the intestacy test only for biological
children of married parents.
16                   ASTRUE v. CAPATO

                     Opinion of the Court

ence under Chevron, 467 U. S. 837.
   Chevron deference is appropriate “when it appears that
Congress delegated authority to the agency generally to
make rules carrying the force of law, and that the agency
interpretation claiming deference was promulgated in the
exercise of that authority.” United States v. Mead Corp.,
533 U. S. 218, 226–227 (2001). Here, as already noted, the
SSA’s longstanding interpretation is set forth in regu-
lations published after notice-and-comment rulemaking.
See supra, at 6–7. Congress gave the Commissioner au-
thority to promulgate rules “necessary or appropriate to
carry out” the Commissioner’s functions and the relevant
statutory provisions. See 42 U. S. C. §§405(a), 902(a)(5).
The Commissioner’s regulations are neither “arbitrary or
capricious in substance, [n]or manifestly contrary to the
statute.” Mayo Foundation for Medical Ed. and Research
v. United States, 562 U. S. ___, ___ (2011) (slip op., at 7)
(internal quotation marks omitted). They thus warrant
the Court’s approbation. See Barnhart v. Walton, 535
U. S. 212, 217–222, 225 (2002) (deferring to the Commis-
sioner’s “considerable authority” to interpret the Social
Security Act).
                             V
  Tragic circumstances—Robert Capato’s death before he
and his wife could raise a family—gave rise to this case.
But the law Congress enacted calls for resolution of Karen
Capato’s application for child’s insurance benefits by
reference to state intestacy law. We cannot replace that
reference by creating a uniform federal rule the statute’s
text scarcely supports.
                       *      *    *
  For the reasons stated, the judgment of the Court of Ap-
peals for the Third Circuit is reversed, and the case is re-
manded for further proceedings consistent with this opinion.

                                             It is so ordered.
