OPINION OF THE COURT
BARRY, Circuit Judge.David Mackins appeals his sentence of 360 months for conspiracy to distribute and possession with intent to distribute crack cocaine. He raises several issues regarding that sentence, only one of which need deter us long. That issue, simply *265stated, is this: does a prior sentence imposed as the result of an Alford plea qualify as a “prior sentence” under U.S.S.G. § 4A1.2(a)(l) for purposes of computing a defendant’s criminal history category under § 4A1.1? Upon reviewing the principles enunciated in North Carolina v. Alford, 400 U.S. 25, 91 S.Ct. 160, 27 L.Ed.2d 162 (1970), we are persuaded, as was the District Court, that the answer is “yes.”1
We are also asked to review whether the District Court erred in imposing a two-level upward adjustment pursuant to § 3B1.4 for Mackins’s use of a minor in committing his offense, and whether the Court erred in refusing to grant Mackins a greater downward departure under § 5K1.1 than the one level he, in fact, received. We find no error in the imposition of the two-level adjustment and lack jurisdiction to review the District Court’s discretionary decision to depart only one level. See United States v. Khalil, 132 F.3d 897, 898 (3d Cir.1997).
I.
Beginning in the spring of 1997, .David Mackins ran a drug distribution operation in Williamsport, Pennsylvania. Briefly summarized, Mackins brought multiple ounce quantities of crack cocaine from New York City into Williamsport, and there enlisted the help of local residents to sell the drugs to street level purchasers. LaPeace Rashie Upshaw and Jerome Staples assisted Mackins with his drug activities in New York City. It is estimated that during the course of the operation between 500 and 1500 grams of crack cocaine were sold.
On September 22, 1998, a federal grand jury returned a three-count superseding indictment charging Mackins, Upshaw and Staples with conspiracy to distribute and possession with intent to distribute cocaine and cocaine base in violation of 21 U.S.C. § 846 (Count I) and possession with intent to distribute the same in violation of 21 U.S.C. § 841(a)(2) (Counts II, III and IV). Upshaw entered into a plea agreement with the government, while Mackins and Staples proceeded to trial. Before commencing the second day of trial, however, Mackins and Staples entered into plea agreements, and Mackins pled guilty to Count I of the superseding indictment on January 20,1999.
Mackins’s Presentence Investigation Report (“PSR”) was then prepared. Beginning with a base offense level of thirty-six, see § 2D1.1(c)(2), a two-level adjustment was added as a specific offense characteristic for Mackins’s possession of a dangerous weapon, see § 2Dl.l(b)(l). In addition, a two-level adjustment was added for Mackins’s role in the offense as an organizer or leader of criminal activity. See § 3Bl.l(c). Finally, a two-level reduction was awarded in light of Mackins’s acceptance of responsibility. See § 3El.l(a). Mackins’s total offense level, therefore, was thirty-eight.
With respect to Mackins’s criminal history category, two prior sentences were considered for a total of five points. See § 4A1.1. The first was by way of a 1991 conviction for robbery for which Mackins received a sentence of 2 to 6 years imprisonment. See § 4Al.l(a) (three points). The second was by way of a 1994 attempted grand larceny conviction on his plea of guilty for which he received a one-year sentence, essentially being sentenced to time served. See § 4Al.l(b) (two points). In addition, two points were added pursuant to § 4Al.l(d) because Mackins was on parole at the time he committed the instant offense, and one point was added because the instant offense was committed less than two years after his release from imprisonment on a sentence counted under § 4Al.l(b). See § 4Al.l(e). The eight total criminal history points established a *266criminal history category of IV, which, in conjunction with the total offense level of thirty-eight, resulted in a guideline imprisonment range of 324 to 405 months.
Mackins objected to the use of the sentence for attempted grand larceny to compute his criminal history category because that sentence was the result of an Alford plea. He objected, as well, when the Court raised the possibility that a two-level upward adjustment was warranted pursuant to § 3B1.4 because Mackins had used a minor, namely co-defendant Staples, to commit the offense. Although Mackins “coneede[d that] the court likely has the power to raise sentencing issues sua sponte,” he, nonetheless, argued that the Court should not do so here because the government had failed to object when the adjustment did not appear in the PSR. In the alternative, Mackins argued that the adjustment should not apply because, “[a]lthough Staples was not over 18 years of age throughout the course of the conspiracy,” he was also “not a child of tender years” and he “voluntarily” participated in the drug activities.
The District Court was not persuaded. First, the Court determined that an Alford plea is an adjudication of guilt and, therefore, Mackins’s Alford plea was properly included for purposes of establishing his criminal history category. Second, the Court found not only that “[t]here is no question that the two-level upward adjustment [pursuant to § 3B1.4] applies,” but that the Court has the responsibility and duty to raise such issues on its own.
Given the one-level downward departure pursuant to § 5K1.1 and the two-level adjustment pursuant to § 3B1.4, Mackins’s total offense level became thirty-nine. With a criminal history category of IV, his applicable guideline imprisonment range was 360 months to life. On November 16, 1999, the District Court sentenced Mac-kins to 360 months. This appeal followed.
II.
We exercise appellate review pursuant to 18 U.S.C. § 3742(a) and (e) and 28 U.S.C. § 1291. The District Court’s interpretation of a sentencing guideline presents a legal question over which we exercise plenary review. See United States v. Ceccarani, 98 F.3d 126, 129 (3d Cir.1996). Where, however, the District Court’s decision is based “on factual determinations, we review for clear error.” United States v. Isaza-Zapata, 148 F.3d 236, 237 (3d Cir.1998).
A. Alfordpleas and U.S.S.G. § 4-Al.l
The most interesting issue on appeal, and one as to which there is a dearth of caselaw in this or any other court, is Mac-kins’s contention that the District Court erred in calculating his criminal history category because it counted the sentence on his Alford plea.2 As noted earlier, pursuant to U.S.S.G. § 4Al.l(b), two criminal history points are assessed “for each prior sentence of imprisonment of at least sixty days,” but not exceeding one year. Section 4A1.2(a)(l) defines a “prior sentence” as “any sentence previously imposed upon adjudication of guilt, whether by guilty plea, trial, or plea of nolo contendere, for conduct not part of the instant offense.” Id. No other terms are defined in the guideline or in the commentary which follows.
Mackins argues that, “by definition, only if the defendant has acknowledged factual guilt by entry of a guilty plea, been found to be factually guilty as a result of a trial, or acknowledges the government has sufficient evidence, which if found credible, would support a finding of guilty is there an ‘adjudication of guilt’ usable i[n] calcu*267lating criminal history.” He contends that an Alford plea lacks the factual basis from which to conclude that the defendant is factually guilty of the offense. Instead, he submits, in an Alford plea the defendant asserts “factual innocence or denies guilt,” but accepts the disposition in order to obtain a favorable sentence.
The origin of what has become known as an Alford plea—North Carolina v. Alford, 400 U.S. 25, 91 S.Ct. 160, 27 L.Ed.2d 162 (1970)—must, of course, inform our decision. Alford was a defendant who had been indicted for first-degree murder, a capital offense in North Carolina. Given the strength of the state’s evidence against him, Alford’s attorney recommended that he plead guilty to a dharge of second-degree murder, thereby avoiding the possibility of a death sentence. Prior to accepting his plea, the trial court heard a summary presentation of the state’s case, including the sworn testimony of several witnesses who testified, inter alia, that Alford had “stated his intention to kill the victim” shortly before the murder “and returned home with the declaration that he had carried out the killing.” Id. at 28, 91 S.Ct. 160. Alford insisted that he was innocent, but nonetheless confirmed his desire to plead guilty “because he faced the threat of the death penalty if he did not do so.” Id. The trial court accepted his plea.
In subsequent federal habeas corpus proceedings, Alford challenged the volun-tariness of his guilty plea, arguing “it was the product of fear and coercion.” Id. at 29, 91 S.Ct. 160. The Court of Appeals for the Fourth Circuit agreed and held that Alford’s plea of guilty “should ... have been rejected because [it was] impermissi-bly induced by his desire to eliminate the possibility of a death sentence.” Id. at 30, 91 S.Ct. 160.
The Supreme .Court, however, disagreed, and made clear that a defendant’s desire to avoid a potential death sentence “does not necessarily demonstrate that the plea of guilty was not the product of a free and rational choice.” Id. at 31, 91 S.Ct. 160. The Court then discussed the impact, if any, of Alford’s insistence at the time of pleading guilty that he did not commit the murder. See id. at 32, 91 S.Ct. 160 (recognizing that “[i]f Alford’s statements were to be credited as sincere assertions of innocence, .... it might be argued that the conviction ... was invalid, since his assertion of innocence negatived any admission of guilt”). The Court pointed out its prior approval of nolo contendere pleas, and explained that “[i]mplicit in the nolo conten-dere cases is a recognition that the Constitution does not bar imposition of a prison sentence upon an accused who is unwilling expressly to admit his guilt but who, faced with grim alternatives, is willing to waive his trial and accept the sentence.” Id. at 36, 91 S.Ct. 160. The Court could not “perceive any material difference between a plea that refuses to admit commission of the criminal act and a plea containing a protestation of innocence when, as in the instant case, a defendant intelligently concludes that his interests require entry of a guilty plea and the record before the judge contains strong evidence of actual guilt.” Id. at 37, 91 S.Ct. 160. Indeed, the Court acknowledged that its earlier cases dealing with pleas of nolo contendere “would be directly in point if Alford had simply insisted on his plea but refused to admit the crime.” Id. Although Alford’s case presented a different factual scenario from that found in a plea of nolo contendere, i.e., Alford expressly insisted on his innocence, the Court rejected the argument that it was constitutional error for the trial court to accept the plea given “the strong factual basis for the plea demonstrated by the State and Alford’s clearly expressed desire to enter it.” Id. at 38, 91 S.Ct. 160.
The Court was clearly concerned with the apparent conflict in accepting Alford’s plea of guilty coupled with his assertion of innocence. Nonetheless, relying his interest in pleading guilty, i.e., avoiding a harsher sentence, and the evidence on the record of his actual guilt, the Court was *268persuaded that he could, under such circumstances, plead guilty. Simply put, the Court was persuaded that once a factual basis for guilt is established, the fact that the defendant may continue to proclaim his innocence does not negate the legal conclusion that he is guilty. See, e.g., White Hawk v. Solem, 693 F.2d 825, 829 (8th Cir.1982) (“As long as there is in fact a strong factual basis supporting a guilty plea, it is valid even if the defendant protests his innocence.”); Government of Virgin Islands v. Berry, 631 F.2d 214, 220 n. 3 (3d Cir.1980) (recognizing that, pursuant to Alford, “a guilty plea may be accepted notwithstanding the defendant’s protestation of innocence”).
As Alford and the cases which followed in its wake made clear, however, there must always exist some factual basis' for a conclusion of guilt before a court can accept an Alford plea; indeed, a factual basis for such a conclusion is “an essential part” of an Alford plea. Willett v. Georgia, 608 F.2d 538, 540 (5th Cir.1979) (“In the face of a claim of innocence a judicial finding of some factual basis for defendant’s guilt is an essential part of the constitutionally-required finding of a voluntary and intelligent decision to plead guilty.”); United States v. Casscles, 494 F.2d 397, 399-400 (2d Cir.1974) (explaining that the District Court took “too narrow a view of Alford” by simply focusing on the fact that the defendant “made a voluntary and intelligent choice” to plead guilty without making sure “that there was a factual basis for the plea”). Accordingly, we conclude that an Alford plea is, without doubt, an adjudication of guilt and is no different than any other guilty plea for purposes of § 4A1.1.
We, therefore, reject Mackins’s contention that the drafters of the Sentencing Guidelines, by not including the Alford disposition in the definition of “prior sentence” in § 4A1.2(a)(l), intended that it not be counted under § 4A1.1. Its omission from § 4A1.2(a)(l) most likely reflects an understanding that it was unnecessary to list it as a separate disposition. As we have, hopefully, satisfactorily explained, an Alford plea is simply a guilty plea, with evidence in the record of guilt, typically accompanied by the defendant’s protestation of innocence and his or her unequivocal desire to enter the plea. See 400 U.S. at 38, 91 S.Ct. 160. That the defendant asserts his or her innocence, however, does not change the fact that he or she ultimately enters a guilty plea. Thus, as the government succinctly states, “[tjhere is no such thing [as an Alford disposition], at least not separate and distinct from a plea of guilty.”3
Maekins, nonetheless, argues that his Alford plea should not be regarded as an “adjudication of guilt” because the underlying record at the time he pled guilty to attempted grand larceny lacked a factual basis from which it could be concluded that he was guilty of the charged offense. He claims that “[t]here is not one iota of evidence that the government had a ‘strong case’, an ‘overwhelming’ case, or that the evidence against [him] ‘substantially negated his claim of innocence.’ ”
Even assuming that Maekins made a “claim of innocence” at that time, and the record is far from clear on that point, his argument amounts to an attack on the underlying factual basis for his *269Alford plea. 4 In that regard, he is no different than a defendant who, having been convicted by a jury at some prior time, argues before a District Court at the time of sentencing on his new conviction that the prior conviction should not be included under § 4A1.1 because the verdict was based on legally insufficient evidence. It is a well-settled principle that, with very limited exceptions, a prior conviction cannot be collaterally attacked in the District Court at the time of sentencing on a new conviction. See Moore v. United States, 178 F.3d 994, 997 (8th Cir.) (“Generally, defendants may not collaterally attack pri- or convictions used for sentencing enhancements.”), cert. denied, — U.S. —, 120 S.Ct. 356, 145 L.Ed.2d 278 (1999); United States v. Arango-Montoya, 61 F.3d 1331, 1336 (7th Cir.1995) (“[A] prior conviction may be collaterally attacked at sentencing only where the defendant claims that he was deprived of counsel in violation of Gideon [v. Wainwright, 372 U.S. 335, 83 S.Ct. 792, 9 L.Ed.2d 799 (1963)7.”) (citation omitted); United States v. Jones, 27 F.3d 50, 52 (2d Cir.1994) (“[A] defendant may not collaterally attack prior state court felony convictions during a federal sentencing hearing unless the defendant was deprived of counsel in the state court proceedings.”); see also United States v. Thomas, 42 F.3d 823, 824 (3d Cir.1994) (“[A] district court, when sentencing a defendant classified as a career offender under section 4B1.1, cannot entertain a constitutional challenge to the underlying convictions except in a case in which the defendant’s right to counsel had been denied.”); United States v. Garcia, 42 F.3d 573, 581 (10th Cir.1994) (“[W]ith the exception of a collateral attack based on the complete denial of counsel, a district court sentencing a defendant under the career offender provisions of the Guidelines cannot consider a collateral attack on a prior conviction.”). Moreover, a Note to § 4A1.2 makes it clear that “this guideline and commentary do not confer upon the defendant any right to attack collaterally a prior conviction or sentence beyond any such rights otherwise recognized in law.” U.S.S.G. § 4A1.2, comment, (n.6). Accordingly, we accord Mackins’s Alford plea the same finality we accord any other “adjudication of guilt, whether by guilty plea, trial, or plea of nolo contendere.” Id.
In sum, because an Alford plea is an adjudication of guilt under § 4A1.2(a)(1), any sentence imposed pursuant to an Alford plea is a “prior sentence” for purposes of § 4A1.1. The District Court, therefore, did not err by including the sentence on Mackins’s Alford plea in the calculation of his criminal history category.
B. Enhancement for use of a minor
We will swiftly dispose of Mackins’s remaining contentions. He argues, as we noted at the outset, that the District Court should not have raised the applicability of a two-level adjustment pursuant to § 3B1.4 for use of a minor, i.e., co-defendant Staples, sua sponte. He asserts, as well, that the Court erred in imposing that adjustment because the record lacks “a factual basis for determining that Staples became part of the conspiracy while still a minor.”
We reject both contentions. First, the District Court did not err in raising the applicability of § 3B1.4 sua sponte, although, to be sure, it could not have imposed the adjustment unless the parties had been notified and been given an opportunity to brief the issue prior to sentencing, which they were. Cf. Burns v. United States, 501 U.S. 129, 138, 111 S.Ct. 2182, 115 L.Ed.2d 123 (1991) (“We hold that before a district court can depart upward on a ground not identified as a ground for upward departure either in the presentence report or in a prehearing submission by the Government, [Federal Rule *270of Criminal Procedure] 32 requires that the district court give the parties reasonable notice that it is contemplating such a ruling.”)- As for Mackins’s contention that the record is not clear as to whether Staples was a minor when he joined the conspiracy, that contention is not only raised for the first time in this appeal, but also contradicts his concession before the District Court that “Staples was not over 18 years of age throughout the course of the conspiracy.” We, therefore, review the adjustment solely for plain error. See United States v. Knobloch, 131 F.3d 366, 370 (3d Cir.1997). Upon a review of the record, we find that the District Court did not commit error, much less plain error.
III.
For the foregoing reasons, we will affirm the judgment of the District Court.
. As, of course, we will discuss more fully, an Alford plea generally refers to a guilty plea entered into by a defendant while expressly maintaining his or her innocence. North Carolina v. Alford, 400 U.S. 25, 91 S.Ct. 160, 27 L.Ed.2d 162 (1970).
. No one disputes that Mackins’s guilty plea to attempted grand larceny should be characterized as an Alford plea. The state court, when accepting the plea, did not elicit an admission of guilt from Mackins and it appears that his sole motivation for pleading guilty was because the plea allowed him to be released on time served as opposed to remaining incarcerated while awaiting a trial date to be set.
. Parenthetically, we observe that a Note to § 8A1.2 states that " '[p]rior criminal adjudication1 means conviction by trial, plea of guilty (including an Alford plea), or plea of nolo contendere." § 8A1.2, comment, (n. 3(g)). Chapter Eight of the Guidelines, dealing with the sentencing of organizations, however, was added by amendment on November 1, 1991. In contrast, the language of § 4A1.2(a)(1) at issue in this case was enacted on November 1, 1987. Not to have included an Alford plea in § 4A1.2(a)(l) and its inclusion in § 8A1.2, four years later, cannot be read to evidence an intent on the part of the drafters of the Guidelines to exclude Alford pleas from § 4A1.2(a)(l). To the contrary, the Note to § 8A1.2 could be read as evidencing an understanding by the drafters of § 8A1.2 that, as we have concluded, an Alford plea is nothing more than a plea of guilty.
. Although it is not relevant for purposes of our discussion, because it is relevant to our dissenting colleague's analysis, we point out that the transcripts of Mackins's Alford plea lack any protestations by Mackins of his innocence. See App. at 34a-38a.