STANDARD OF REVIEW
We review de novo a district court’s ruling on a motion to dismiss for failure to state a claim upon which relief can be granted. See Rae v. Union Bank, 725 F.2d 478, 479 (9th Cir.1984). A motion to dismiss should not be granted unless it appears that the plaintiff can prove no set of facts in support of his claim that would entitle him to relief. Conley v. Gibson, 355 U.S. 41, 45-46, 78 S.Ct. 99, 101-02, 2 L.Ed.2d 80 (1957).
The availability of collateral estoppel is also subject to de novo review. Davis & Cox v. Summa Corp., 751 F.2d 1507, 1519 (9th Cir.1985); United States v. Geophysical Corp., 732 F.2d 693, 697 (9th Cir.1984). If collateral estoppel is available, we review a district court’s decision to apply it for an abuse of discretion. Davis & Cox, 751 F.2d at 1519; Geophysical Corp., 732 F.2d at 697.
DISCUSSION
I. Consideration of Administrative Records
There is some ambiguity concerning the procedural posture of this case. South Bay initiated the dismissal by filing a motion to dismiss under Fed.R.Civ.P. 12(b)(6). The minute order indicates that the district court granted the motion as a motion to dismiss. The district court’s subsequent decision, however, indicates that the court considered the exhibits and granted the motion as one for summary judgment pursuant to Fed.R.Civ.P. 56.
Rule 12(b) states that if, on a motion to dismiss for failure to state a claim upon which relief can be granted, matters outside the pleadings are presented and not excluded by the court, the motion shall be treated as one for summary judgment and disposed of as provided in Rule 56. It is reversible error for a court to grant a motion to dismiss that has been converted to one for summary judgment, without providing all parties a reasonable opportunity to present material relevant to a Rule 56 motion. Erlich v. Glasner, 374 F.2d 681, 683 (9th Cir.1967); Costen v. Pauline’s Sportswear Inc., 391 F.2d 81, 84-85 (9th Cir.1968).
To enable the court to determine whether the Unemployment Insurance Appeals Board’s decision has a collateral estoppel effect on Mack’s age discrimination claim, South Bay requested the district court to take judicial notice of the state administrative records attached to the motion to dismiss as exhibits. Consequently, Mack contends that this court should reverse the district court because it violated Rule 56 by not giving him the requisite notice and reasonable opportunity to submit all pertinent material.
On a motion to dismiss, however, a court may take judicial notice of facts outside the pleadings. Sears, Roebuck & Co. v. Metropolitan Engravers, Ltd., 245 F.2d 67, 70 (9th Cir.1956); 5 C. Wright & A. Miller, Federal Practice & Procedure, § 1363 at 659-60 (1969).3 Moreover, a court may take judicial notice of “records and reports of administrative bodies.” Interstate Natural Gas Co. v. Southern California Gas Co., 209 F.2d 380, 385 (9th Cir.1953). Therefore, on a motion to dismiss a court may properly look beyond the complaint to matters of public record and doing so does not convert a Rule 12(b)(6) motion to one for summary judgment. See Phillips v. Bureau of Prisons, 591 F.2d 966, 969 (D.C.Cir.1979).
Accordingly, we treat the district court’s decision as a dismissal for failure to state a claim under Rule 12(b)(6) and hold that the district court did not commit reversible error in not complying with Rule 56, because summary judgment was not in fact involved.
II. Collateral Estoppel Effect of Unreviewed State Administrative Board’s Determination
South Bay contends, and the district court held, that unreviewed Unemployment
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Mack, himself, relied on this precedent in requesting the district court to take judicial notice of the same administrative records in opposing the motion to dismiss his pendent state law claim.