Justice Thomas
delivered the opinion of the Court.
In 28 U. S. C. § 994(h), Congress directed the United States Sentencing Commission (Commission) to “assure” that the Sentencing Guidelines specify a prison sentence “at or near the maximum term authorized for categories of” adult offenders who commit their third felony drug offense or violent crime. We are asked to decide whether, by “maximum term authorized,” Congress meant (1) the maximum term available for the offense of conviction including any applicable statutory sentencing enhancements, as the United States argues, or (2) the maximum term available without such enhancements, as the Commission has determined. We conclude that the Commission’s interpretation is inconsistent with § 994(h)’s plain language, and therefore hold that “maximum term authorized” must be read to include all applicable statutory sentencing enhancements.
I
A
In 1984, Congress created the Commission and charged it with “establishing] sentencing policies and practices for the Federal criminal justice system.” 28 U. S. C. § 991; see Mistretta v. United States, 488 U. S. 361, 367-370 (1989). The Commission, however, was not granted unbounded discretion. Instead,. Congress articulated general goals for federal sentencing and imposed upon the Commission a variety of specific requirements. See §§994(b)-(n). Among those requirements, Congress directed that the Commission
“shall assure that the guidelines specify a sentence to a term of imprisonment at or near the maximum term authorized for categories of defendants in which the defendant is eighteen years old or older and—
“(1) has been convicted of a felony that is—
“(A) a crime of violence; or
“(B) an offense described in section 401 of the Controlled Substances Act (21 U. S. C. 841). . .; and
“(2) has previously been convicted of two or more prior [such] felonies . . . .” 28 U. S. C. § 994(h).
The Commission sought to implement this directive by promulgating the “Career Offender Guideline,” which created a table of enhanced total offense levels to be used in calculating sentences for “career offenders.” United States Sentencing Commission, Guidelines Manual §4B1.1 (Nov. 1987) (USSG). Pursuant to that Guideline, each defendant who qualifies for career offender status is automatically placed in criminal history “Category VI,” the highest available under the Guidelines. The table then assigns the appropriate offense level based on the so-called “offense statutory maximum.”
When the Commission coined the phrase “offense statutory maximum,” it defined it, unhelpfully, as “the maximum term of imprisonment authorized for the offense of conviction.” USSG App. C, amdt. 267 (Nov. 1989) (adding §4B1.1, comment., n. 2). Neither the Career Offender Guideline itself, however, nor the accompanying commentary designated which “maximum term” was to be used when federal law established a basic statutory maximum for persons convicted of a particular offense, but also provided an enhanced maximum penalty for career offenders convicted of that same offense. The Courts of Appeals, required to choose between sentencing “at or near the maximum” of the base sentence, or of the base sentence plus the relevant statutory enhancements, uniformly concluded that the “offense statutory maximum” for a defendant with prior convictions was the enhanced maximum term.
The Commission subsequently amended the Career Offender Guideline’s commentary to preclude consideration of statutory enhancements in calculating the “offense statutory maximum.” Rejecting the approach prevailing in the Courts of Appeals, the Commission defined the phrase “offense statutory maximum” as:
“the maximum term of imprisonment authorized for the offense of conviction that is a crime of violence or controlled substance offense, not including any increase in that maximum term under a sentencing enhancement provision that applies because of the defendant’s prior criminal record . . . USSG App. C, amdt. 506 (Nov. 1994) (amending USSG §4B1.1, comment., n. 2).
Pursuant to its authority under 28 U. S. C. § 994(u), the Commission opted to give Amendment 506 retroactive effect, providing sentencing courts with discretion to reduce sentences imposed before the amendment’s November 1, 1994, effective date. See USSG §1B1.10(c) (Nov. 1996).
B
Prior to the adoption of Amendment 506, respondents George LaBonte, Alfred Lawrence Hunnewell, and Stephen Dyer were convicted of various federal controlled substance offenses in the United States District Court for the District of Maine. Each respondent qualified as a career offender under USSG §4B1.1 (Nov. 1987), had received the required notice that an enhanced penalty would be sought, and was sentenced under the Career Offender Guideline using the enhancement. The First Circuit affirmed each respondent’s conviction and sentence. Following the adoption of Amendment 506, however, each respondent sought a reduction in his sentence. In the cases of respondents Dyer and Hun-newell, the District Court found that the amendment was contrary to 21 U. S. C. § 841(b)(1)(C) and 28 U. S. C. § 994(h), and refused to reduce the sentences. In respondent La-Bonte’s case, however, a different judge of the same District Court upheld the amendment and reduced LaBonte’s sentence. The First Circuit consolidated the ensuing appeals and a divided panel, applying the approach set forth in Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984), upheld Amendment 506 as an appropriate exercise of the Commission’s discretion. 70 F. 3d 1396, 1403-1409 (1995). The First Circuit looked to the statutory language and “f[ou]nd no clear congressional directive regarding the meaning of the term ‘maximum’ as that term is used in section 994(h).” Id., at 1406. In the court’s view, the meaning of the word “maximum” was influenced by its presence in the phrase “ ‘maximum term authorized for [certain] categories of defendants.’” Id., at 1404 (bracketed term in original). While acknowledging that the phrase could apply exclusively to that category of repeat offenders for whom the Government filed a notice to seek sentence enhancement, the court also observed that the word “categories” could plausibly be defined “to include all offenders (or all repeat offenders) charged with transgressing the same criminal statute, regardless of whether the prosecution chooses to invoke the sentence-enhancing mechanism against a particular defendant.” Id., at 1404-1405 (emphasis added). Under the latter view, the court reasoned, the- word “maximum” would necessarily refer to the unenhanced statutory maximum “since this represents the highest possible sentence applicable to all defendants in the category.” Id., at 1405.
Based on that perceived ambiguity, the court explained that the “Career Offender Guideline, read through the prism of Amendment 506, adopts an entirely plausible version of the categorical approach that the statute suggests.” Id., at 1407. The court thus held that the Career Offender Guideline, as construed under Amendment 506, was a reasonable implementation of § 994(h)’s command to designate sentences at or near the authorized maximum term. Id., at 1409.
In validating Amendment 506, the First Circuit here reached the same conclusion as the Ninth Circuit later did in United States v. Dunn, 80 F. 3d 402, 404 (1996). Five other Courts of Appeals, however, have reached the opposite conclusion, finding Amendment 506 at odds with the plain language of § 994(h). We granted certiorari to resolve this conflict, 518 U. S. 1016 (1996), and now reverse.
II
Congress has delegated to the Commission “significant discretion in formulating guidelines” for sentencing convicted federal offenders. Mistretta, 488 U. S., at 377. Broad as that discretion may be, however, it must bow to the specific directives of Congress. In determining whether Amendment 506 accurately reflects Congress’ intent, we turn, as we must, to the statutory language. If the Commission’s revised commentary is at odds with § 994(h)’s plain language, it must give way. Cf. Stinson v. United States, 508 U. S. 36, 38 (1993) (explaining that the Guidelines commentary “is authoritative unless it violates the Constitution or a federal statute”).
In § 994(h), Congress directed the Commission to “assure” that for adult offenders who commit their third felony drug offense or crime of violence, the Guidelines prescribe a sentence of imprisonment “at or near the maximum term authorized.” 28 U. S. C. § 994(h). We do not start from the premise that this language is imprecise. Instead, we assume that in drafting this legislation, Congress said what it meant. Giving the words used their “ordinary meaning,” Moskal v. United States, 498 U. S. 103, 108 (1990), we find that the word “maximum” most naturally connotes the “greatest quantity or value attainable in a given case.” Webster’s New International Dictionary 1396 (2d ed. 1958); Black’s Law Dictionary 979 (6th ed. 1990) (“The highest or greatest amount, quality, value, or degree”). We similarly conclude, and the parties do not dispute, that the phrase “term authorized” refers not to the period of incarceration specified by the Guidelines, but to that permitted by the applicable sentencing statutes. Accordingly, the phrase “maximum term authorized” should be construed as requiring the “highest” or “greatest” sentence allowed by statute.
Respondents, however, argue that “maximum term authorized” refers only to the highest penalty authorized by the offense of conviction, excluding any statutory sentencing enhancements. We find little merit in that contention. In calculating the “highest” term prescribed for a specific offense, it is not sufficient merely to identify the basic penalty associated with that offense. Congress has expressly provided enhanced maximum penalties for certain categories of repeat offenders in an effort to treat them more harshly than other offenders. Section 994(h) explicitly refers, for example, to 21 U. S. C. § 841, which establishes a base “term of imprisonment of not more than 20 years” for certain drug traffickers, but then adds that “[i]f any person commits such a violation after a prior conviction for a felony drug offense has become final, such person shall be sentenced to a term of imprisonment of not more than 30 years.” § 841(b)(1)(C). Where Congress has enacted a base penalty for first-time offenders or nonqualifying repeat offenders, and an enhanced penalty for qualifying repeat offenders, the “maximum term authorized” for the qualifying repeat offenders is the enhanced, not the base, term. As a consequence, the “maximum term authorized” for repeat offenders convicted under § 841(b)(1)(C) is 30 years — the enhanced statutory maximum — not the unenhanced maximum of 20 years.
Respondents’ assertion that § 994(h) is ambiguous is based, at least in part, on a strained construction of the phrase “categories of defendants.” They claim that the word “categories” can be defined broadly to encompass all repeat offenders charged with violating the same criminal statute— including those for whom the Government did not file a notice under § 851(a)(1) and who are therefore ineligible for the penalty enhancement. See n. 1, supra. If “categories of defendants” is defined in this way, respondents argue, a sentence “at or near the maximum term authorized” for this broader “category” of repeat offenders would necessarily permit only the unenhanced maximum because this is the highest possible sentence that could apply to all of the defendants within that category.
We see at least two serious flaws in this reasoning. First, respondents’ construction of the word “categories” is overin-elusive because it subsumes within a single category both defendants who have received notice under § 851(a)(1) and those who have not. The statutory scheme, however, obviously contemplates two distinct categories of repeat offenders for each possible crime. The Commission is no more free to ignore this distinction than it is to ignore the distinction made between those defendants who distributed certain controlled substances and those whose distribution also directly resulted in the death of a user. See, e. g., 21 U. S. C. § 841(b)(1)(C). Thus, for defendants who have received the notice under § 851(a)(1), as respondents did here, the “maximum term authorized” is the enhanced term. For defendants who did not receive the notice, the unenhanced maximum applies.
Second, to read the phrase “categories of defendants” as respondents suggest would largely eviscerate the penalty enhancements Congress enacted in statutes such as § 841. We are unwilling to read § 994(h) as essentially rendering meaningless entire provisions of other statutes to which it expressly refers. Under respondents’ novel construction, a repeat drug or violent felon could only receive a sentence at or near the maximum allowed for defendants who had no such prior qualifying convictions or who had never received the notice under § 851(a)(1). Indeed, if this interpretation of the term “categories” were adopted, a sentencing court could be forbidden to impose the enhanced maximum penalty. Congress surely did not establish enhanced penalties for repeat offenders only to have the Commission render them a virtual nullity.
Respondents further seek to circumvent §994(h)’s plain meaning by claiming that Amendment 506 satisfies Congress’ mandate to sentence repeat offenders “at or near” the maximum sentence authorized. The flexibility afforded by the phrase “at or near,” respondents contend, justifies the Commission’s decision to rely on the unenhanced maximum. This statutory phrase unquestionably permits a certain degree of flexibility for upward and downward departures and adjustments. The pertinent issue, however, “is not how close the sentence must be to the statutory maximum, but to which statutory maximum it must be close.” United States v. Fountain, 83 F. 3d 946, 952 (CA8 1996), cert. pending, No. 96-6001. Whatever latitude § 994(h) affords the Commission in deciding how close a sentence must come to the maximum to be “near” it, the statute does not license the Commission to select as the relevant “maximum term” a sentence that is different from the congressionally authorized maximum term.
Finally, respondents rely heavily on the Commission’s stated justifications for choosing the unenhanced maximum. We are unmoved. First, the Commission asserted that, by precluding the use of the statutory enhancements, Amendment 506 “avoids unwarranted double counting” of the defendant’s prior offenses. 59 Fed. Reg. 23608, 23609 (1994). That argument is entirely beside the point. Congress has instructed the Commission to assure that the sentences of repeat offenders closely track the statutory maximum. The number of steps the Commission employs to achieve that requirement is unimportant, provided the Commission’s mechanism results in sentences “at or near” the “maximum term authorized.”
Second, respondents invoke the Commission’s assertion that its amended commentary eliminates “unwarranted disparity associated with variations in the exercise of prosecu-tional discretion in seeking enhanced penalties based on prior convictions.” Ibid. As we understand it, this argument posits that if the Government provides notice under § 851(a)(1) to one defendant, but not to another, the resulting difference in the maximum possible term is an “unwarranted disparity.” Insofar as prosecutors, as a practical matter, may be able to determine whether a particular defendant will be subject to the enhanced statutory maximum, any such discretion would be similar to the discretion a prosecutor exercises when he decides what, if any, charges to bring against a criminal suspect. Such discretion is an integral feature of the criminal justice system, and is appropriate, so long as it is not based upon improper factors. See United States v. Armstrong, 517 U. S. 456, 464-465 (1996); Wayte v. United States, 470 U. S. 598, 607 (1985). Any disparity in the maximum statutory penalties between defendants who do and those who do not receive the notice is a foreseeable— but hardly improper — consequence of the statutory notice requirement.
III
In sum, we hold that the phrase “at or near the maximum term authorized” is unambiguous and requires a court to sentence a career offender “at or near” the “maximum” prison term available once all relevant statutory sentencing enhancements are taken into account. Accordingly, we reverse the judgment below and remand the case for further proceedings consistent with this opinion.
It is so ordered.
We note that imposition of an enhanced penalty is not automatic. Such a penalty may not be imposed unless the Government files an information notifying the defendant in advance of trial (or prior to the acceptance of a plea) that it will rely on that defendant’s prior convictions to seek a penalty enhancement. 21 U. S. C. § 851(a)(1). If the Government does not file such notice, however, the lower sentencing range will be applied even though the defendant may otherwise be eligible for the increased penalty.
See United States v. Smith, 984 F. 2d 1084, 1087 (CA10), cert. denied, 510 U. S. 873 (1993); United States v. Garrett, 959 F. 2d 1005, 1009-1011 (CADC 1992); United States v. Amis, 926 F. 2d 328, 329-330 (CA3 1991); United States v. Sanchez-Lopez, 879 F. 2d 541, 558-560 (CA9 1989).
See United States v. McQuilkin, 97 F. 3d 723, 731-733 (CA3 1996), cert. pending, No. 96-6810; United States v. Branham, 97 F. 3d 835, 845-846 (CA6 1996); United States v. Hernandez, 79 F. 3d 584, 595-601 (CA7 1996), cert. pending, Nos. 95-8469, 95-9335; United States v. Fountain, 83 F. 3d 946, 950-953 (CA8 1996), cert. pending, No. 96-6001; United States v. Novey, 78 F. 3d 1483, 1486-1488 (CA10 1996), cert. pending, No. 95-8791.
Indeed, the Commission has explicitly recognized that “the phrase ‘maximum term authorized’ should be construed as the maximum term authorized by statute.” USSG §4B1.1, comment., backg’d (Nov. 1987) (emphasis added). And, in our view, the phrase refers to all applicable statutes that would affect the district court’s calculation of the prison term. Contrary to the dissent’s suggestion, however, 18 U. S. C. § 3584 does not affect the maximum term authorized. Section 3584 merely instructs a sentencing court whether to run “multiple terms of imprisonment” consecutively or concurrently; it says nothing about how the individual term is to be calculated. §3584 (emphasis added). Of course, § 3584(c), which the dissent highlights, post, at 770, directs that “[mjultiple terms of imprisonment... shall be treated for administrative purposes as a single, aggregate term of imprisonment.” 18 U. S. C, § 3584(c) (emphasis added). Each of the sections cited by the dissent falls within this “administrative purposes” carve-out, which in no way undercuts, and in fact plainly bolsters, our point.
Respondents’ reliance on United States v. R. L. C., 503 U. S. 291 (1992), is inapposite. There, we construed 18 U. S. C. § 5037(c), which provides that the sentence ordered by a court for a juvenile delinquent may not extend beyond “the maximum term of imprisonment that would be authorized if the juvenile had been tried and convicted as an adult.” We held that the applicable “maximum” term authorized was the upper limit of the Guidelines range that would apply to a similarly situated adult offender. 503 U. S., at 306-307. R. L. C. involved a directive to a sentencing court, however, whereas 28 U. S. C. § 994(h) is a directive to the Commission. Because § 994(h) is designed to cabin the Commission’s discretion in the promulgation of guidelines for career offenders, it would be entirely circular to suggest that the Commission had complied with § 994(h) merely by specifying sentences “at or near” the top of the Guidelines range. The Commission itself recognizes that the “maximum term authorized” within the meaning of § 994(h) is the statutory maximum, not the otherwise applicable Guidelines maximum. See n. 4, supra.
Inasmuch as we find the statute at issue here unambiguous, we need not decide whether the Commission is owed deference under Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984).