2 THE CHIEF JUSTICE finds the Medicaid expansion vulnerable because it took participating States by surprise. Ante, at 54. “A State could hardly anticipate that Congress” would endeavor to “transform [the Medicaid program] so dramatically,” he states. Ante, at 54–55. For the notion that States must be able to foresee, when they signup, alterations Congress might make later on, THE CHIEF JUSTICE cites only one case: Pennhurst State School and Hospital v. Halderman, 451 U. S. 1. In Pennhurst, residents of a state-run, federally funded institution for the mentally disabled complained of abusive treatment and inhumane conditions in alleged violation of the Developmentally Disabled Assistance and Bill of Rights Act. 451 U. S., at 5–6. We held that the State was not answerable in damages for violating conditions it did not “voluntarily and knowingly accep[t].” Id., at 17, 27. Inspecting the statutory language and legislative history, we found that the Act did not “unambiguously” impose the requirement on which the plaintiffs relied: that they receive appropriate treatment in the least restrictive environment. Id., at 17–18. Satisfied that Congress had not clearly conditioned the States’ receipt of federal funds on the States’ provision of such treatment, we declined to read such a requirement into the Act. Congress’ spending power, we concluded, “does not include surprising participating States with post acceptance or ‘retroactive’ conditions.” Id., at 24–25. Pennhurst thus instructs that “if Congress intends to impose a condition on the grant of federal moneys, it must do so unambiguously.” Ante, at 53 (quoting Pennhurst, 451 U. S., at 17). That requirement is met in this case.Section 2001 does not take effect until 2014. The ACA makes perfectly clear what will be required of States that accept Medicaid funding after that date: They must extend eligibility to adults with incomes no more than 133% of the federal poverty line. See 42 U. S. C. §1396a(a)(10)(A) (i)(VIII) (2006 ed. and Supp. IV). THE CHIEF JUSTICE appears to find in Pennhurst a requirement that, when spending legislation is first passed, or when States first enlist in the federal program, Congress must provide clear notice of conditions it might later impose. If I understand his point correctly, it was incumbent on Congress, in 1965, to warn the States clearly of the size and shape potential changes to Medicaid might take. And absent such notice, sizable changes could not be made mandatory. Our decisions do not support such a requirement.   THE CHIEF JUSTICE observes that “Spending Clause legislations much in the nature of a contract.” Ante, at 46 (internal quotation marks omitted). See also post, at 33 (joint opinion of SCALIA, KENNEDY, THOMAS, and ALITO, JJ.) (same). But the Court previously has recognized that “unlike normal contractual undertakings, federal grant programs originate in and remain governed by statutory provisions expressing the judgment of Congress concerning desirable public policy.” Bennett v. Kentucky Dept. of Ed., 470 U. S. 656, 669 (1985). In Bennett v. New Jersey, 470 U. S. 632 (1985), the Secretary of Education sought to recoup Title I funds  based on the State’s noncompliance, from 1970 to 1972, with a 1978 amendment to Title I. Relying on Pennhurst, we rejected the Secretary’s attempt to recover funds based on the States’ alleged violation of a rule that did not exist when the State accepted and spent the funds. See 470 U. S., at 640 (“New Jersey[,] when it applied for and received Title I funds for the years 1970–1972[,] had no basis to believe that the propriety of the expenditures would be judged by any standards other than the ones in effect at the time.” (citing Pennhurst, 451 U. S., at 17, 24– 25; emphasis added)).  Title I of the Elementary and Secondary Education Act of 1965 provided federal grants to finance supplemental educational programs in school districts with high concentrations of children from low-income families. See Bennett v. New Jersey, 470 U. S. 632, 634–635 (1985) (citing Pub. L. No. 89–10, 79 Stat. 27).When amendment of an existing grant program has no such retroactive effect, however, we have upheld Congress’ instruction. In Bennett v. Kentucky Dept. of Ed., 470 U. S. 656 (1985), the Secretary sued to recapture Title I funds based on the Commonwealth’s 1974 violation of a spending condition Congress added to Title I in 1970. Rejecting Kentucky’s argument pinned to Pennhurst, we held that the Commonwealth suffered no surprise after accepting the federal funds. Kentucky was therefore obliged to re- turn the money. 470 U. S., at 665–666, 673–674. The conditions imposed were to be assessed as of 1974, in light of “the legal requirements in place when the grants were made,” id., at 670, not as of 1965, when Title I was originally enacted. As these decisions show, Pennhurst’s rule demands that conditions on federal funds be unambiguously clear at the time a State receives and uses the money—not at the time,perhaps years earlier, when Congress passed the law establishing the program. See also Dole, 483 U. S., at 208 (finding Pennhurst satisfied based on the clarity of the Federal Aid Highway Act as amended in 1984, without looking back to 1956, the year of the Act’s adoption). In any event, from the start, the Medicaid Act put States on notice that the program could be changed: “The right to alter, amend, or repeal any provision of [Medicaid],” the statute has read since 1965, “is hereby reserved to the Congress.” 42 U. S. C. §1304. The “effect of these few simple words” has long been settled. See National Railroad Passenger Corporation v. Atchison, T. & S. F. R. Co., 470 U. S. 451, 467–468, n. 22 (1985) (citing Sinking Fund Cases, 99 U. S. 700, 720 (1879)). By reserving the right to “alter, amend, [or] repeal” a spending program,Congress “has given special notice of its intention to retain . . . full and complete power to make such alterations and amendments . . . as come within the just scope of legislative power.” Id., at 720. Our decision in Bowen v. Public Agencies Opposed to Social Security Entrapment, 477 U. S. 41, 51–52 (1986), is guiding here. As enacted in 1935, the Social Security Act did not cover state employees. Id., at 44. In response to pressure from States that wanted coverage for their employees, Congress, in 1950, amended the Act to allow States to opt into the program. Id., at 45. The statutory provision giving States this option expressly permitted them to withdraw from the program. Ibid. Beginning in the late 1970’s, States increasingly exercised the option to withdraw. Id., at 46. Concerned that withdrawals were threatening the integrity of Social Security, Congress repealed the termination provision.Congress thereby changed Social Security from a program voluntary for the States to one from which they could not escape. Id., at 48. California objected, arguing that the change impermissibly deprived it of a right to withdraw from Social Security. Id., at 49–50. We unanimously rejected California’s argument. Id., at 51–53. By including in the Act “a clause expressly reserving to it ‘[t]he right to alter, amend, or repeal any provision’ of the Act,” we held, Congress put States on notice that the Act “created no contractual rights.” Id., at 51–52. The States therefore had no law-based ground on which to complain about the amendment, despite the significant character of the change. THE CHIEF JUSTICE nevertheless would rewrite §1304to countenance only the “right to alter somewhat,” or “amend, but not too much.” Congress, however, did not so qualify §1304. Indeed, Congress retained discretion to “repeal” Medicaid, wiping it out entirely. Cf. Delta Air Lines, Inc. v. August, 450 U. S. 346, 368 (1981) (Rehnquist,J., dissenting) (invoking “the common-sense maxim that the greater includes the lesser”). As Bowen indicates, no State could reasonably have read §1304 as reserving to Congress authority to make adjustments only if modestly sized. In fact, no State proceeded on that understanding. In compliance with Medicaid regulations, each State expressly undertook to abide by future Medicaid changes. See 42 CFR §430.12(c)(1) (2011) (“The [state Medicaid] plan must provide that it will be amended whenever necessary to reflect . . . [c]hanges in Federal law, regulations, policy interpretations, or court decisions.”). Whenever a State notifies the Federal Government of a change in its own Medicaid program, the State certifies both that it knows the federally set terms of participation may change, and that it will abide by those changes as a condition of continued participation. See, e.g., Florida Agency for Health Care Admin., State Plan Under Title XIX of the Social Security Act Medical Assistance Program §7.1, p. 86 (Oct.6, 1992). THE CHIEF JUSTICE insists that the most recent expansion, in contrast to its predecessors, “accomplishes a shift in kind, not merely degree.” Ante, at 53. But why was Medicaid altered only in degree, not in kind, when Congress required States to cover millions of children and pregnant women? See supra, at 41–42. Congress did not “merely alte[r] and expan[d] the boundaries of ” the Aid to Families with Dependent Children program. But see ante, at 53–55. Rather, Congress required participating States to provide coverage tied to the federal poverty level (as it later did in the ACA), rather than to the AFDC program. See Brief for National Health Law Program et al. as Amici Curiae 16–18. In short, given §1304, this Court’s construction of §1304’s language in Bowen, and the enlargement of Medicaid in the years since 1965,  a State would be hard put to complain that it lacked fair notice when,in 2010, Congress altered Medicaid to embrace a larger portion of the Nation’s poor.[/S]  Note, in this regard, the extension of Social Security, which began in 1935 as an old-age pension program, then expanded to include survivor benefits in 1939 and disability benefits in 1956. See Social Security Act, ch. 531, 49 Stat. 622–625; Social Security Act Amendments of 1939, 53 Stat. 1364–1365; Social Security Amendments of1956, ch. 836, §103, 70 Stat. 815–816.