FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

BLACKIE ALVAREZ,                      
               Plaintiff-Appellant,
                v.                         No. 06-35068
JEAN HILL, Superintendent; MAX
WILLIAMS; MITCH MORROW; J.                  D.C. No.
                                          CV-04-00884-BR
GILMORE; S. FRANKE; T.
                                             OPINION
O’CONNOR; SONJA HOYT; T.
ARMSTRONG; S. BABB; CAIN; RIDER,
             Defendants-Appellees.
                                      
       Appeal from the United States District Court
                for the District of Oregon
        Anna J. Brown, District Judge, Presiding

                  Argued and Submitted
          February 6, 2008—Seattle, Washington

                   Filed March 13, 2008

     Before: Raymond C. Fisher, Ronald M. Gould and
              Sandra S. Ikuta, Circuit Judges.

                 Opinion by Judge Fisher




                           2457
2460                  ALVAREZ v. HILL


                        COUNSEL

Blackie F. Alvarez, pro se; John B. Schochet (argued), Dorsey
& Whitney LLP, Seattle, Washington, and Michael B. King,
Talmadge Law Group PLLC, Tukwila, Washington, for the
plaintiff-appellant.

Hardy Myers, Attorney General, Mary H. Williams, Solicitor
General, Michael C. Livingston, Senior Assistant Attorney
General, Rolf C. Moan (argued), Assistant Attorney General,
Office of the Oregon Attorney General, Salem, Oregon, for
the defendants-appellees.
                             ALVAREZ v. HILL                            2461
James McCurdy, Lindsey Hart Neil & Weigler, LLP, Port-
land, Oregon, for the amicus curiae ACLU Foundation of
Oregon, Inc.


                                OPINION

FISHER, Circuit Judge:

   We revisit in this appeal the longstanding principle that
federal complaints plead claims, not causes of action or stat-
utes or legal theories. Blackie Alvarez (“Alvarez”) brought
suit alleging that prison officials substantially burdened his
religious exercise by denying him various accommodations.
Those officials (“appellees”) now insist that Alvarez’s failure
to specifically plead in his complaint a violation of the Reli-
gious Land Use and Institutionalized Persons Act of 2000
(“RLUIPA”), see 42 U.S.C. § 2000cc-1, bars his argument
that the district court erred in not analyzing his religious exer-
cise claims under RLUIPA, which establishes a more protec-
tive standard than does the First Amendment. They are plainly
incorrect. We have jurisdiction under 28 U.S.C. § 1291, and
we affirm in part, reverse in part and remand.

                           BACKGROUND

  In June 2004, Alvarez, then an inmate at the Oregon State
River Correctional Institution, filed a pro se complaint seek-
ing redress for violations of the “First [and] Fourteenth
Amendments” on the part of prison officials.1 Alvarez alleged
  1
    Alvarez also claimed that he was deprived of access to legal materials
in violation of Bounds v. Smith, 

, 828 (1977). We affirm the
district court’s grant of summary judgment as to this claim because Alva-
rez has not “allege[d] injury, such as inability to file a complaint or defend
against a charge” resulting from deficiencies in access. Jones v. Blanas,

, 936 (9th Cir. 2004). Failure to show that a “nonfrivolous
legal claim had been frustrated” is fatal to his Bounds claim. Lewis v.
Casey, 

, 353 & n.4 (1996).
2462                        ALVAREZ v. HILL
that they “ ‘burden[ed] substantially’ . . . his religion” by
denying him the “right to participate and practice the Sweat
Lodge Ceremony and Sacred Pipe Ceremony” and by making
it “difficult if not impossible to communicate with any of his
tribe[’]s religious representatives.” He also alleged that
they forbade him from wearing a headband, consuming
tobacco for ceremonial purposes and participating in group wor-
ship.2 Four months later, Alvarez supplemented his complaint
with a self-styled “Motion in Support of Original Complaint
with Law.” Alvarez asserted there that the district court had
“supplemental jurisdiction” of his free exercise claims under
“Religious Land Use and Institutionalized Persons Act, 42
U.S.C.A. § 2000cc,” and other civil rights statutes.

   Appellees thereafter filed for summary judgment in
December 2004. They argued that although the prison’s poli-
cies burdened Alvarez’s constitutional free exercise rights,
they were “reasonably related to legitimate penological inter-
ests” and consequently satisfied the standard set forth in Tur-
ner v. Safley, 

, 89 (1987). Responding directly to
appellees’ reliance on Turner, Alvarez opposed their “conclu-
sory” assertions of the governmental interest in security and
safety, referring to the more stringent “standard set by the
R.L.U.I.P.A. 2000.” He asserted this was so because RLUIPA
“explicitly changed the standard by which restrictions on the
free exercise of religion are to be judged, and clearly applies
in the prison context.” Citing Mayweathers v. Newland, 

(9th Cir. 2002), and 42 U.S.C. § 2000cc-1(a)(1),
Alvarez contended that RLUIPA “restores a higher standard
which requires the state to demonstrate . . . that its regulations
or practices are ‘in furtherance of a compelling government-
[al] interest.’ ” Additionally, he identified RLUIPA as provid-
ing a statutory ground for relief apart from the Free Exercise
  2
   In addition to declaratory and injunctive relief, Alvarez sought a total
of $55,000 in damages, so his subsequent release from custody has not
mooted this action. See Rhodes v. Robinson, 

, 566 n.8 (9th
Cir. 2005).
                         ALVAREZ v. HILL                      2463
Clause. He explained he was bringing suit under the “Reli-
gious Land Use and Institutionalized Persons Act
(R.L.U.I.P.A.) . . . in relation to . . . substantial burdening and
interference with Sacred Religious Objects and Practices. And
violation of plaintiff’s First Amendment (free exercise).”
(Emphasis added.) Prison officials were “not only violating
plaintiff’s constitutional rights, but the Religious Land Use
and Institutionalized Persons Act.” (Emphasis added.)

   The appellees’ reply acknowledged that Alvarez’s “claim
must be analyzed under the Religious Land Use and Institu-
tionalized Persons Act.” His “claims of an RLUIPA violation
[were] without merit,” they argued, given the serious “safety
and security” concerns justifying restrictions on religious
practice while an inmate was in disciplinary housing.

   The district court granted summary judgment in favor of
appellees. Citing Freeman v. Arpaio, 

, 736 (9th
Cir. 1997), a religious exercise case litigated before the pas-
sage of RLUIPA, the court held that an inmate could prevail
on a free exercise claim only by showing that prison officials
“burdened the practice of [his] religion by preventing him
from engaging in conduct mandated by his religious faith.”
The court found the restrictions on Alvarez’s religious exer-
cise were not a “substantial burden on the practice of his reli-
gion.” Furthermore, the court held that insofar as officials had
produced “sufficient evidence” that the restrictions furthered
the “legitimate institutional goals” of maintaining prison
safety and security, they did not “rise to the level of a consti-
tutional violation.”

                 STANDARD OF REVIEW

  A district court’s grant of summary judgment is reviewed
de novo. Blanford v. Sacramento County, 

,
1114 (9th Cir. 2005). “Viewing the evidence in the light most
favorable to the nonmoving party . . . we must determine
whether the district court correctly applied the relevant sub-
2464                       ALVAREZ v. HILL
stantive law and whether there are any genuine issues of
material fact.” Galvin v. Hay, 

, 745 (9th Cir.
2004).

                                    I.

   [1] We agree with Alvarez’s contention that summary judg-
ment would have been inappropriate on the available record
had RLUIPA’s standard been applied to his religious exercise
claim. Under Turner, which governs inmate free exercise
claims brought under the First Amendment, prison restrictions
will be upheld as long as they are “reasonably related to legit-
imate penological interests.” Warsoldier v. Woodford, 

, 997-98 (9th Cir. 2005) (quoting 

). By contrast, RLUIPA disallows policies that impose “a
substantial burden on . . . religious exercise” unless the bur-
den “furthers ‘a compelling governmental interest,’ and does
so by ‘the least restrictive means.’ ” 

(quoting 42
U.S.C. § 2000cc-1(a)).

   [2] The district court’s analysis did not take account of
RLUIPA, which “accord[s] religious exercise heightened pro-
tection from government-imposed burdens.” Cutter v. Wilkin-
son, 

, 714 (2005). In finding that Alvarez’s
religious exercise was not substantially burdened, the district
court required him to show he was prevented from “engaging
in conduct mandated by his religious faith.”3 RLUIPA, how-
ever, defines “religious exercise” to include “any exercise of
religion, whether or not compelled by, or central to, a system
of religious belief.” 42 U.S.C. § 2000cc-5(7)(A) (emphasis
added). Moreover, the district court accepted the govern-
  3
    As we noted in Shakur v. Schriro, No. 05-16705, ___ F.3d ___, 

at *3-4 (9th Cir. Jan. 23, 2008), Freeman’s requirement that
an inmate must show that the prison had burdened “conduct mandated by
his faith” to state a viable free exercise claim under the First Amendment
has been undercut by Employment Div., Dep’t of Human Resources v.
Smith, 

(1990). Cf. 

.
                        ALVAREZ v. HILL                     2465
ment’s proffered justifications without engaging in the more
searching scrutiny RLUIPA requires. Under RLUIPA, prison
officials bear the burden of establishing that the restriction
challenged is the “least restrictive alternative to achieve” a
compelling governmental interest. See 

. “[N]o longer can prison officials justify restrictions on
religious exercise by simply citing to the need to maintain
order and security in a prison.” Greene v. Solano County Jail,
No. 06-16957, ___ F.3d ___, 

at *6 (9th Cir.
Jan. 22, 2008). They now must demonstrate that they “actu-
ally considered and rejected the efficacy of less restrictive
measures before adopting the challenged practice.” War-

.

                               II.

   [3] Appellees offer no rebuttal to Alvarez’s suggestion that
genuine issues of material fact existed as to whether their
restrictions on his religious exercise were the least restrictive
means of maintaining prison security, and so essentially con-
cede that a RLUIPA claim would have survived summary
judgment. Instead, they assert that Alvarez pled only a First
Amendment claim, because his “complaint [did] not identify
RLUIPA as the basis for a separate claim.” The contention
that his complaint’s omission of a citation to RLUIPA pre-
cludes Alvarez from advancing legal arguments based on that
statute is entirely meritless. We hold that Alvarez’s RLUIPA
claim was presented to the district court because his com-
plaint and subsequent filings provided appellees with “fair
notice” of that claim, even though the statute was not cited in
the complaint itself. See Bell Atl. Corp. v. Twombly, 

, 1969 (2007).

   [4] The form complaint used by Alvarez, which was pro-
vided by the prison itself, instructed inmates to “[s]tate here
as briefly as possible the facts of your case”; they were “not
[to] give any legal arguments or cite any cases or statutes.”
(Emphasis in original.) In the space for indicating the “civil
2466                     ALVAREZ v. HILL
right” underlying his claim, Alvarez wrote that the appellees
had violated his “First [and] Fourteenth Amendment[ ]” rights
by “ ‘burdening substantially’ . . . his religion.” Alvarez then
pled with commendable — even greater than necessary —
particularity how prison officials were doing just that. See
Leatherman v. Tarrant County Narcotics Intelligence and
Coordination Unit, 

, 168 (1993). He further
alleged that prison officials lacked any valid justification for
these restrictions because the proscribed activities involved no
“breach to security procedure.” Because Alvarez’s complaint
contained factual allegations establishing a “plausible” entitle-
ment to relief under RLUIPA, Alvarez satisfied the minimal
notice pleading requirements of Rule 8 of the Federal Rules
of Civil Procedure. See 

& n.14;
see also Skaff v. Meridien N. Am. Beverly Hills, LLC, 

, 839 (9th Cir. 2007) (“Rule 8’s concluding admon-
ishment that ‘[a]ll pleadings shall be so construed as to do
substantial justice’ confirms the liberality with which we
should judge whether a complaint gives the defendant suffi-
cient notice . . . .”) (quoting Fed. R. Civ. P. 8(f)). This conclu-
sion is bolstered by the “less stringent standards” used to
assess whether a pro se inmate’s complaint places prison offi-
cials on notice of the nature of his claims. Jackson v. Carey,

, 757 (9th Cir. 2003).

   [5] Appellees’ argument that Alvarez’s complaint failed to
“state a claim” under RLUIPA because he did not cite the
statute misapprehends the function of pleadings in federal
practice. Notice pleading requires the plaintiff to set forth in
his complaint claims for relief, not causes of action, statutes
or legal theories. See Fed. R. Civ. P. 8(a)(2). “This simplified
notice pleading standard relies on liberal discovery rules and
summary judgment motions to define disputed facts and
issues and to dispose of unmeritorious claims.” Swierkiewicz
v. Sorema N.A., 

, 512 (2002). A complaint need
not identify the statutory or constitutional source of the claim
raised in order to survive a motion to dismiss. See, e.g.,
Sagana v. Tenorio, 

, 736-37 (9th Cir. 2004);
                        ALVAREZ v. HILL                      2467
Austin v. Terhune, 

, 1171 (9th Cir. 2004);
Cabrera v. Martin, 

, 745 (9th Cir. 1992).

   [6] As contemplated by the regime of liberal notice plead-
ing, Alvarez’s subsequent filings refined the factual allega-
tions and legal theories supporting his religious exercise
claims. See Neitzke v. Williams, 

, 329-30 & n.9
(1989) (recognizing “[r]esponsive pleadings . . . may be nec-
essary for a pro se plaintiff to clarify his legal theories”). His
reference to RLUIPA in his “Motion in Support of Original
Complaint with Law” initially surfaced the statutory basis for
his claim. His opposition to summary judgment described at
length the RLUIPA standard and urged the court to apply it
to the facts alleged in his complaint. Appellees exalt form
over substance by arguing that Alvarez occasionally confused
the relationship between RLUIPA and the First Amendment
and so “effectively state[ed] that [his] citations to RLUIPA
. . . are not to be read” as asserting a “second, independent
cause of action.” There is no suggestion that appellees were
led astray by Alvarez’s failure to appreciate the technical dis-
tinctions they now invoke. Cf. Fed. R. Civ. P. 8(d)(1); Davis
v. Passman, 

, 237-38 & n.15 (1979). Indeed,
appellees’ reply to Alvarez’s opposition expressly recognized
the applicability of RLUIPA, conclusively establishing that
they had fair notice that a statutory religious exercise claim
also was being presented to the district court. See Lee v. City
of Los Angeles, 

, 682 (9th Cir. 2001).

    [7] Moreover, because Alvarez proceeded pro se, the dis-
trict court was required to “afford [him] the benefit of any
doubt” in ascertaining what claims he “raised in his complaint
and argued to the district court.” Morrison v. Hall, 

, 899 n.2 (9th Cir. 2001) (emphasis added) (internal quota-
tion marks omitted); see also Erickson v. Pardus, 

, 2200 (2007) (per curiam) (noting that complaint “alone
. . . [was] enough to satisfy Rule 8(a)(2),” but that pro se peti-
tioner also “bolstered his claim by making more specific alle-
gations . . . in later filings”). Even when the plaintiff is
2468                    ALVAREZ v. HILL
represented by counsel, and counsel initially “misconceived
the proper legal theory of the claim,” summary judgment does
not follow if the plaintiff is entitled “to relief on some other
legal theory” and “requested as much.” Crull v. GEM Ins.
Co., 

, 1391 (9th Cir. 1995).

   [8] Finally, we dispose of appellees’ argument that Hender-
son v. Terhune, 

(9th Cir. 2004), precludes a
RLUIPA claim when the complaint cites only the First
Amendment. There, we “express[ed] no opinion about wheth-
er” the challenged regulation violated RLUIPA because the
inmate “brought his claim under the First Amendment, not the
RLUIPA.” 

n.1. Appellees’ reliance on Henderson
is misplaced, because at no point did the plaintiff there even
assert a RLUIPA claim. See 

Here, Alvarez spe-
cifically raised his RLUIPA theory in his post-complaint fil-
ings, thereby apprising appellees before summary judgment
that he was claiming relief under both the First Amendment
and RLUIPA. See Coleman v. Quaker Oats Co., 

, 1292-94 (9th Cir. 2000) (holding that plaintiffs could
not proceed with different theory of liability after close of dis-
covery when defendant would be prejudiced by inability to
develop newly relevant evidence and defenses). Appellees
had notice of and the opportunity to challenge Alvarez’s
RLUIPA claim. Consequently, that claim was properly before
the district court at summary judgment and the court erred in
not addressing it.

   Appellees’ rigid insistence that RLUIPA claims must be
specifically pled in the plaintiff’s complaint is without support
in our precedent and frankly puzzling in view of the lenience
traditionally afforded pro se pleadings and of RLUIPA’s man-
ifest purpose of protecting “institutionalized persons who are
unable freely to attend to their religious needs.” See 

. The “simplified pleading standard applies to
all civil actions, with limited exceptions” provided for by rule
or by statute. See 

. Accordingly,
we hold that RLUIPA claims need satisfy only the ordinary
                        ALVAREZ v. HILL                    2469
requirements of notice pleading, and that a complaint’s failure
to cite RLUIPA does not preclude the plaintiff from subse-
quently asserting a claim based on that statute. Under this
pleading standard, it is sufficient that the complaint, alone or
supplemented by any subsequent filings before summary
judgment, provide the defendant fair notice that the plaintiff
is claiming relief under RLUIPA as well as the First Amend-
ment.

   [9] Having concluded that the district court erred in not
addressing Alvarez’s RLUIPA claim, we vacate its grant of
summary judgment as to his religious exercise claims without
reaching his constitutional arguments in support of reversal.
See Anchustegui v. Dep’t of Agric., 

, 1129 (9th
Cir. 2001).

  This panel shall retain jurisdiction over any subsequent
appeals in this matter. Alvarez shall recover his costs on
appeal.

 AFFIRMED IN PART AND REVERSED IN PART;
REMANDED.