with whom Justice Brennan and Justice Marshall join, dissenting.
Today the Court holds that the plain language of a statute applicable by its terms to “any child support payments” com*486pels the conclusion that the statute does not apply to benefits paid to the dependent child of a disabled, retired, or deceased parent for the express purpose of supporting that child. Because I am persuaded that this crabbed interpretation of the statute is neither compelled by its language nor consistent with its purpose, and arbitrarily deprives certain families of a modest but urgently needed welfare benefit, I dissent.
I
I begin, as does the majority, with the plain language of the disregard provision. It refers to “any child support payments received . . . with respect to the dependent child or children in any family applying for or receiving aid to families with dependent children (including support payments collected and paid to the family under section 657(b) of this title).”1 42 U. S. C. §602(a)(8)(A)(vi) (1982 ed., Supp. V) (emphasis added). This language does not support the majority’s narrow interpretation. The word “any” generally means all forms or types of the thing mentioned. When coupled with the parenthetical phrase “including ... ,” it indicates that “support payments collected and paid” by the State constitute one type within the larger universe of “child support payments.” As the majority recognizes, § 602(a)(26)(A) requires all applicants for AFDC to “assign the State any rights to support from any other person . . . .” Thus, support payments from absent parents will almost always fall within the parenthetical clause referring to “support payments collected and paid” by the State. The plain words of the disregard provision indicate that such payments are only one of various types of child support payments; limiting the meaning of child support to an absent *487parent’s payments renders the statutory language “any child support payments . . . including ...” meaningless.
The majority’s insistence that the ordinary meaning of the term “child support” excludes Title II payments makes little sense. Title II is a program of mandatory wage deductions, designed to ensure that a worker’s dependents will have some income, should the worker retire, die, or become disabled. Califano v. Boles, 443 U. S. 282, 283 (1979) (Title II “attempts to obviate, through a program of forced savings, the economic dislocations that may otherwise accompany old age, disability, or the death of a breadwinner”). Thus, the worker is legally compelled to set aside a portion of his wages in order to earn benefits used to support his dependent children in the event he becomes unable to do so himself. A child is entitled to Title II payments only if he or she lived with, or received financial support from, the insured worker—that is, only if the relationship between the child and the insured worker would (or did) give rise to a legally enforceable support obligation. 42 U. S. C. § 402(d) (1982 ed. and Supp. V). The sole and express purpose of Title II children’s benefits is to support dependent children. Jimenez v. Weinberger, 417 U. S. 628, 634 (1974) (“[T]he primary purpose of the . . . Social Security scheme is to provide support for dependents of a disabled wage earner”); Mathews v. Lucas, 427 U. S. 495, 507 (1976) (“[T]he Secretary explains the design of the statutory scheme ... as a program to provide for all children of deceased [or disabled] insureds who can demonstrate their ‘need’ in terms of dependency”); see also Mathews v. De Castro, 429 U. S. 181, 185-186, and n. 6 (1976). It is unlawful to use Title II payments for any other purpose. 42 U. S. C. §408(e) (1982 ed.).2
*488How are Title II payments different from court-ordered payments by an absent parent? Their source is the same: a parent’s wages or assets.3 Their purpose is the same: to provide for the needs of a dependent child, in lieu of the support of a working parent living in the home. The majority does not even attempt to explain why the common usage and understanding of the term “child support” would include all the types of payments the Secretary says the disregard provision covers — legally compulsory payments from absent parents, voluntary payments,4 and even spousal support payments5—but would exclude Title II payments.
Nonetheless, the majority insists that Title II payments do not constitute “child support.” The majority points to the use of the term “child support” in Part D of Title IV to refer to court-ordered support payments by absent parents. This begs the question. Naturally, Congress was referring to compulsory support payments in Part D, because that part of the statute is concerned with “enforcing the support obligations owed by absent parents to their children.” 42 U. S. C. § 651 (1982 ed., Supp. V). Other types of child support, such as payments voluntarily made by absent parents, or payments made by the Government on behalf of dead, disabled, or retired parents, do not involve the same problems of en*489forcement.6 Nowhere in Part D did Congress actually define “child support,” nor does Part D or any other provision of Title IV indicate that Congress thought the term “child support” referred only to compulsory payments or only to payments made directly by the absent parent.
The majority relies on the maxim of statutory construction that identical words in two related statutes, or in different parts of the same statute, are intended to have the same meaning. Ante, at 484. Like all such maxims, however, this is merely a general assumption, and is not always valid or applicable. In Erlenbaugh v. United States, 409 U. S. 239 (1972), for example, the Court declined to follow this maxim, because it was invoked not simply to resolve any ambiguities or doubts in the statutory language, but, as in this case, “to introduce an exception to the coverage of the [statute] where none is now apparent.” Id., at 245. The Court commented: “This might be a sensible construction of the two statutes if they were intended to serve the same function, but plainly they were not.” Ibid. It went on to explain that the two statutes had different purposes, and the reason for the limited scope of one was absent in the context of the other. Id., at 245-247. See also District of Columbia v. Carter, 409 U. S. 418, 421 (1973) (“At first glance, it might seem logical simply to assume . . . that identical words used in two related statutes were intended to have the same effect. Nevertheless . . . the meaning well may vary to meet the purposes of the law”) (internal quotation marks omitted); Helvering v. Stockholms Enskilda Bank, 293 U. S. 84, 87 (1934) (“[S]ince most words admit of different shades of meaning, susceptible of being expanded or abridged to con*490form to the sense in which they are used, the presumption readily yields [when] the words, though in the same act, are found in . . . dissimilar connections”). This Court’s articulation of the limits of the maxim in Atlantic Cleaners & Dyers, Inc. v. United States, 286 U. S. 427 (1932), bears repeating, for it remains true today:
“But the presumption is not rigid and readily yields whenever there is such variation in the connection in which the words are used as reasonably to warrant the conclusion that they were employed in different parts of the act with different intent .... [T]he meaning well may vary to meet the purposes of the law, to be arrived at by a consideration of the language in which those purposes are expressed, and of the circumstances under which the language was employed. . . .
“It is not unusual for the same word to be used with different meanings in the same act, and there is no rule of statutory construction which precludes the courts from giving to the word the meaning which the legislature intended it should have in each instance.” Id., at 433.
I conclude that the plain language of the statute does not unequivocally support the Secretary’s interpretation. It is equally consistent with the opposite conclusion that Title II payments fall within the broad, inclusive phrase “any child support payments.” It is therefore proper to turn to the purpose and history of the disregard provision for aid in construing that provision.
II
The majority, in its conservatively restrictive approach, makes only passing reference to the hardship brought about by the DEFRA amendments. A closer look at the effect of these amendments is necessary to understand the function of the disregard provision. DEFRA changed the AFDC statutes in two ways relevant here. First, it established *491the “mandatory filing unit” requirement that a family’s application for AFDC benefits must take into account any income received by any member of the family, including all children living in the same household. 42 U. S. C. § 602(a)(38) (1982 ed., Supp. V). See Bowen v. Gilliard, 483 U. S. 587, 589 (1987).
Under prior law, parents could choose to exclude from their AFDC applications children who received income from other sources. This exclusion, in some circumstances, was advantageous to the family; although the family then would not receive AFDC funds for the excluded child, that child’s income would not be considered in determining its overall AFDC eligibility. Thus, in situations where a child’s separate income was greater than the incremental amount of AFDC benefits the family would receive for that child, the family was better off not counting the child in its AFDC application.
Along with the new requirement, however, Congress enacted the provision at issue here. The Court in Gilliard explained:
“Because the 1984 amendments forced families to include in the filing unit children for whom support payments were being received, the practical effect was that many families’ total income was reduced. The burden of the change was mitigated somewhat by a separate amendment providing that the first $50 of child support collected by the State must be remitted to the family and not counted as income for the purpose of determining its benefit level.” Id., at 594.7
*492The legislative history of the DEFRA amendments supports the conclusion that the disregard provision was intended to mitigate the harsh effects of the amendments. The mandatory filing-unit provision was first proposed by the Secretary in 1982, but it was dropped in Conference because of opposition in the House. See H. R. Conf. Rep. No. 97-760, p. 446 (1982). In 1983, the Secretary again proposed this provision, and it was approved by the Senate. S. Rep. No. 98-300, p. 165 (1983). Again, there was opposition in the House, and consideration of the provision was carried over to the next session. House Committee on Ways and Means, Description of the Administration’s Fiscal Year 1985 Budget, Comm. Print No. 98-24, pp. 25, 29-30 (1984). In 1984, the provision was added by the Senate amendments to H. R. 4170, the bill that became the Deficit Reduction Act of 1984 (DEFRA). The Report of the House-Senate Conference Committee explains:
“The conference agreement follows the Senate amendment with the following modification: a monthly disregard of $50 of child support received by a family is established.” H. R. Conf. Rep. No. 98-861, p. 1407 (1984).
Neither the House bill nor the Senate bill had contained a disregard provision prior to the Conference, nor is there any discussion in the legislative history of such a provision. The only plausible explanation for its sudden appearance is that it was meant to assuage the concerns of some Members of Congress about the harsh impact of the DEFRA amendments and thus to facilitate the passage of the mandatory filing-unit requirement.
The burden of the DEFRA amendments falls equally on families with children receiving Title II benefits and on those with children receiving court-ordered support payments. The mitigating purpose of the disregard provision therefore applies equally to both categories of families. The purpose and history of the disregard provision support the Court of Appeals’ interpretation of that provision and resolve any *493ambiguity as to the meaning of the statutory words “any child support payments.”
Since the Secretary’s interpretation of the disregard rule is not compelled by the language of the statute and is not supported by its purpose and legislative history, it is not entitled to deference and should be rejected by this Court. See NLRB v. Food & Commercial Workers, 484 U. S. 112, 123 (1987) (“On a pure question of statutory construction, our first job is to try to determine congressional intent, using ‘traditional tools of statutory construction.’ If we can do so, then that interpretation must be given effect, and the regulations at issue must be fully consistent with it”); Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 843, n. 9 (1984) (“The judiciary is the final authority on issues of statutory construction and must reject administrative constructions which are contrary to clear congressional intent.... If a court, employing traditional tools of statutory construction, ascertains that Congress had an intention on the precise question at issue, that intention is the law and must be given effect”).
III
Even if the meaning of “child support” in the disregard provision were ambiguous, however, the Secretary’s interpretation should still be rejected because it is so arbitrary as not to reflect a “permissible construction of the statute.” Id., at 843. The Secretary’s position is that the disregard applies to legally compulsory child support payments, voluntary child support payments, and spousal support payments by absent parents, but not to Title II payments. See nn. 4 and 5, supra.
Consider, for example, a family consisting of a mother and three children. One of the children is of a prior marriage and receives support from her absent father. The father voluntarily sets aside a portion of his wages every month and sends them to the mother for the child’s support. The disregard *494provision applies. See n. 4, supra. Then the father retires and stops his voluntary contributions, but the child now receives Title II benefits each month. The disregard provision, according to the Secretary, does not apply. But then the mother obtains a court order obligating the father to make child support payments each month, and he does so. The disregard provision applies. Then the father asks the court to amend the support order, so that the Title II benefits are used to satisfy his support obligation. See n. 2, supra. The disregard provision, according to the Secretary, does not apply.
Throughout this example, the child’s and her family’s financial needs remain the same. The impact of the mandatory filing-unit requirement, forcing the family to count the child’s income in its AFDC application and thus reducing the level of its benefits, remains the same. The source of the child’s income—her father’s earnings—and the purpose of that income—to fulfill his duty to provide for the needs of his dependent child—remain the same. But the applicability of the disregard provision changes with the vagaries of the Secretary’s regulations.
The Secretary argues that his interpretation of the disregard provision is rational because the disregard serves as an incentive for absent parents to make support payments and for custodial parents to cooperate in enforcement efforts (since $50 of those payments directly benefits the family and does not merely reimburse the State for AFDC). But there is simply no indication that Congress intended to limit the applicability of the disregard provision to situations in which it would serve as an incentive. There is no mention of such a purpose in the legislative history of the provision; moreover, the Secretary points to no discussion of the need for such an incentive anywhere in the legislative history of the DEFRA amendments.8
*495Even if the disregard rule were intended to serve as an incentive, that does not justify applying the disregard to all court-ordered support payments, but not to Title II benefits. Not all court-ordered support payments depend on the voluntary compliance of the absent parent; some are deducted directly from the absent parent’s wages—just like Title II deductions. See n. 3, supra. Also, insofar as the disregard serves as an incentive for the custodial parent to help collect support payments, that purpose applies to Title II benefits as well as to court-ordered support payments. To qualify for Title II benefits, the custodial parent, on behalf of the child, must complete an application and, if necessary, establish paternity. If the disregard does not apply to Title II benefits, so that they serve only to reduce a family’s AFDC eligibility, the custodial parent has no financial incentive to apply for them.
Thus, I believe that the Secretary cannot provide any rational explanation for his view that the disregard provision does not apply to Title II payments. Even assuming that the provision is ambiguous and that Chevron deference is to *496be considered, I cannot in good conscience defer to an administrative interpretation that results in an arbitrary and irrational reduction of welfare benefits to certain needy families. I view with regret the Court’s acquiescence in an administrative effort to cut the costs of the AFDC program by any means that are available.
I dissent.
Title 42 U. S. C. §657(b) (1982 ed., Supp. V) provides that, when a state agency collects child or spousal support payments on behalf of a family receiving Aid to Families With Dependent Children (AFDC), it shall pay to the family the first $50 of each month’s payment and retain the rest to reimburse the Government for AFDC benefits.
The overwhelming majority of state courts that have passed on the question have concluded that a parent’s court-ordered child support obligations may be fulfilled by Title II payments, recognizing the functional equivalence of the two types of payments. See, e. g., Stroop v. Bowen, *488870 F. 2d 969, 974-975 (CA4 1989) (collecting cases); Todd v. Norman, 840 F. 2d 608, 614, and n. 4 (CA8 1988) (dissenting opinion).
Although Title II payments are made by a Government agency, not directly by the parent, their ultimate source is the parent’s earnings. See Califano v. Boles, 443 U. S. 282, 283 (1979). Moreover, not all court-ordered support payments are made by the parent; under a mandatory wage-assignment order, child support is deducted automatically from the absent parent’s wages (just as Title II deductions are). See 42 U. S. C. §666(b) (1982 ed., Supp. V).
The Secretary considers voluntary payments by an absent parent to be “child support” within the meaning of the disregard provision. 53 Fed. Reg. 21644 (1988).
See id., at 21642.
The majority’s reliance on the fact that Part D “abounds with references to ‘child support’ in the context of compulsory support funds from absent parents,” ante, at 483, to limit the meaning of “child support” in § 602(a)(8)(A)(vi) appears to be inconsistent with the Secretary’s own interpretation of the disregard provision as including voluntary as well as court-ordered payments. See n. 4, supra.
The $50 disregard, though it may seem to be a small sum, may be a substantial part of a family’s monthly income. In Virginia, respondents’ State of residence, the maximum monthly AFDC payment for a family of three is currently $265. Brief for Respondents 1-2. See 45 CFR § 233.20(a)(2) (1989); Virginia Code § 63.1-110 (Supp. 1990). An additional $50 would be a 19% increase in AFDC benefits.
The Secretary relies on the legislative history of a 1975 provision which allowed 40% of the first $50 of child support collected by the *495state agency to be disregarded in determining the family’s income level. 42 U. S. C. § 657(a)(1) (1982 ed.). This provision, by its express terms, however, is applicable only “during the 15 months beginning July 1, 1975.” In 1975, the statutory obligation of AFDC applicants to assign support rights and cooperate with enforcement efforts had just been established, see 42 U. S. C. §602(a)(26) (1982 ed., Supp. V), and Congress apparently believed that a temporary incentive provision would help to ensure compliance with these new requirements. Such a rule, however, was never again proposed or enacted between 1975 and 1984.
By 1984, the assignment and cooperation requirements were longstanding conditions of AFDC eligibility. Custodial parents who failed to assign their support rights and cooperate in enforcement efforts would know that they stood to lose their AFDC benefits. The very different contexts in which the 1974 and 1984 disregard statutes were enacted thus give an additional reason for this Court’s usual reluctance to infer the intent of one Congress from the views expressed by another. See Russello v. United States, 464 U. S. 16, 26 (1983); Oscar Mayer & Co. v. Evans, 441 U. S. 750, 758 (1979).