                    FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

RESIDENT COUNCILS OF                      
WASHINGTON; WASHINGTON STATE
LONG-TERM CARE OMBUDSMAN
PROGRAM, through Kary W. Hyre,                   No. 05-36065
              Plaintiffs-Appellants,
                v.                                 D.C. No.
                                                CV-04-01691-TSZ
MICHAEL O. LEAVITT,* Secretary,                    OPINION
United States Department of
Health and Human Services,
               Defendant-Appellee.
                                          
         Appeal from the United States District Court
           for the Western District of Washington
          Thomas S. Zilly, District Judge, Presiding

                    Argued and Submitted
              July 12, 2007—Seattle, Washington

                      Filed August 31, 2007

Before: Michael Daly Hawkins and Kim McLane Wardlaw,
Circuit Judges, and Louis H. Pollak,** Senior District Judge.

                   Opinion by Judge Hawkins



   *Michael O. Leavitt is substituted for his predecessor, Tommy G.
Thompson, as Secretary of Health and Human Services. Fed. R. App. P.
43(c)(2).
   **The Honorable Louis H. Pollak, Senior United States District Judge
for the Eastern District of Pennsylvania, sitting by designation.

                                11085
        RESIDENT COUNCILS OF WASHINGTON v. LEAVITT   11087


                       COUNSEL

Eric M. Carlson, National Senior Citizens Law Center, Los
Angeles, California, for the plaintiffs-appellants.
11088    RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
Joshua Waldman, Department of Justice, Civil Division,
Washington, D.C., for the defendant-appellee.

Morris J. Baller, Goldstein, Demchak, Baller, Borgen & Dar-
darian, Oakland, California; Alison E. Hirschel, Michigan
Poverty Law Program, East Lansing, Michigan; Richard J.
Mollot, Long Term Care Community Coalition, New York,
New York, for amici curiae in support of the plaintiffs-
appellants.

Thomas W. Sondag, Portland, Oregon, for amicus curiae in
support of the defendant-appellee.


                         OPINION

HAWKINS, Circuit Judge:

   As we are often called to do, we address a federal agency’s
interpretation of words chosen by Congress and the some-
times tricky shoals of Chevron deference. Resident Councils
of Washington, an organization consisting primarily of nurs-
ing and boarding home residents and their families, and the
Washington State Long-Term Care Ombudsman Program,
representing Washington’s long-term care facility residents
(collectively, “Plaintiffs”), appeal the adverse grant of sum-
mary judgment in their challenge to the Secretary of Health
and Human Services’s (“Secretary” or “agency”) regulations
authorizing states to allow the use of paid feeding assistants
to feed nursing home residents who do not have complicated
feeding problems.

  Plaintiffs contend that the regulations violate the Nursing
Home Reform Law (“Reform Law”), 42 U.S.C. §§ 1395i-3,
1396r, by permitting “nursing or nursing-related services” to
be performed by individuals not authorized by the statute.
They argue that the regulations are not entitled to deference
             RESIDENT COUNCILS OF WASHINGTON v. LEAVITT            11089
because they are contrary to Congress’s express intent and,
alternatively, that the regulations are not based on a permissi-
ble construction of the Reform Law. We have jurisdiction
under 28 U.S.C. § 1291 and affirm.

            FACTS AND PROCEDURAL HISTORY

I.       Statutory Background

   Congress enacted the Reform Law as part of the Omnibus
Budget Reconciliation Act of 1987, Pub. L. No. 100-203,
§§ 4201-4211, 101 Stat. 1330 (codified as amended at 42
U.S.C. §§ 1395i-3, 1396r). The Reform Law’s legislative his-
tory indicates Congress was “deeply troubled that the Federal
government, through the Medicaid program, continues to pay
nursing facilities for providing poor quality care to vulnerable
elderly and disabled beneficiaries.” H.R. Rep. No. 100-391(I)
at 452 (1987). The “central purpose” of the Reform Law was
“to improve the quality of care for Medicaid-eligible nursing
home residents, and either to bring substandard facilities into
compliance with Medicaid quality of care requirements or to
exclude them from the program.” Id.

   To effect this purpose, the Reform Law imposed several
new requirements relating to nursing home1 resident services,
including (1) an annual standardized resident assessment con-
ducted by a registered nurse, 42 U.S.C. §§ 1395i-3(b)(3),
1396r(b)(3); (2) a written plan of care for each resident, id.
§§ 1395i-3(b)(2), 1396r(b)(2); and (3) resident medical care
under a physician’s supervision, id. §§ 1395i-3(b)(6),
1396r(b)(6).

  The Reform Law also prohibits the full-time paid use of
“any individual as a nurse aide in the facility . . . for more
     1
    “Nursing home” refers collectively to what the Medicare statute calls
a “skilled nursing facility,” 42 U.S.C. § 1395i-3(a), and to what the Med-
icaid statute calls a “nursing facility,” id. § 1396r(a).
11090     RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
than 4 months unless the individual . . . has completed a train-
ing and competency evaluation program . . . [and] is compe-
tent to provide nursing or nursing-related services.” Id.
§§ 1395i-3(b)(5)(A), 1396r(b)(5)(A). Congress then specified
that nurse aides are required to complete a minimum of 75
hours of initial training. Id. §§ 1395i-3(f)(2)(A)(i),
1396r(f)(2)(A)(i). Congress defined “nurse aide” to mean
“any individual providing nursing or nursing-related services
to residents,” but excluding any individual who is a “licensed
health professional,” “registered dietician,” or volunteer. Id.
§§ 1395i-3(b)(5)(F), 1386r(b)(5)(F).2 Congress did not further
define “nursing or nursing-related services.”

II.    Regulatory Background

  A)    Initial Regulations

   In 1991, the Department of Health and Human Services
(“HHS”) issued regulations implementing the Reform Law.
See 56 Fed. Reg. 48,880 (Sept. 26, 1991). These regulations
enumerated certain topics to be included in the nurse aide
training curriculum, including “[a]ssisting with eating and
hydration” and “[p]roper feeding techniques.” 42 C.F.R.
§ 483.152(b)(3)(v), (vi).

   The regulations did not, however, further define “nursing or
nursing-related services,” specifying only that “an individual
must be directly involved in patient care to meet the definition
of nurse aide.” 56 Fed. Reg. at 48,890. HHS administrators
subsequently interpreted “nursing or nursing-related services”
in informal letters to include assisting a resident with feeding
and, accordingly, took the view that “feeding assistance”
could only be performed by a nurse aide or statutorily exempt
individual, though it appears the Secretary never made an
official pronouncement to this effect.
  2
   Because these exempted individuals are not subject to regulation, in
our subsequent discussion we focus only on nurse aides.
           RESIDENT COUNCILS OF WASHINGTON v. LEAVITT                11091
  B)    Proposed Regulations

   In March 2002, the Secretary proposed a new rule allowing
states to permit nursing homes to use paid feeding assistants
for residents without complicated feeding problems.3 See
Notice of Proposed Rulemaking, 67 Fed. Reg. 15,149 (Mar.
29, 2002). The notice explained that the new rule was neces-
sary in light of changes in the long-term care industry, includ-
ing a growing shortage of nurse aides, exacerbated by the
time-consuming nature of feeding assistance, an increasing
aged population, and increasing demands on nurse aides. Id.
at 15,150-51. The Secretary described the positive experi-
ences of two states that use paid feeding assistants. Id. at
15,151. The proposed rule’s preamble noted the Secretary’s
conclusion that the proposed change comported with existing
law and that the benefits of the change would outweigh any
risks. Id. Finally, the Secretary acknowledged that the pro-
posed rule constituted a change in policy and solicited public
comment. Id. at 15,150-51.4

  C)     Final Regulations

  After receiving over 6,000 comments, 99% of which sup-
ported the proposed rule,5 the Secretary promulgated the final
  3
     Although the proposed regulations were jointly submitted by the
Administrator of HHS’s Centers for Medicare & Medicaid Services and
the Secretary, for simplicity’s sake, we refer only to the Secretary.
   4
     “There is no provision in Federal regulations for the employment of
nursing home workers who perform only a single task without completing
75 hours of nurse aide training. Currently, residents must be fed by a reg-
istered nurse, licensed practical nurse, or a nurse aide who has completed
75 hours of medical training and who has been certified as competent to
perform all nurse aide tasks.” Id. at 15,151.
   5
     Although Plaintiffs provided evidence that the vast majority of the sup-
porting letters were “form letters,” as the district court held, there is no
reason the Secretary was not entitled to rely on such letters in promulgat-
ing the regulations. That numerous individuals share the same opinion and
pooled their efforts does not undermine their intended show of support.
Indeed, several letters submitted to this court by amici on behalf of Plain-
tiffs appear to be form letters, yet each received our full consideration.
11092      RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
regulations on September 26, 2003. 68 Fed. Reg. 55,528,
55,530 (codified at 42 C.F.R. § 483.35(h)) (Sept. 26, 2003).
The final regulations allow states the option of permitting
nursing homes to use paid feeding assistants subject to certain
limitations.

   Feeding assistants must first successfully complete a state-
approved training course including at least eight hours of
training. 42 C.F.R. §§ 483.35(h)(1)(i), 483.75(q), 483.160(a).
In addition, feeding assistants may feed only those residents
who have no complicated feeding problems (such as difficulty
swallowing, recurrent lung aspirations, and tube or parenteral/
IV feedings). Id. § 483.35(h)(3). Resident eligibility to be fed
by feeding assistants is based “on the charge nurse’s assess-
ment and the resident’s latest assessment and plan of care.”
Id. § 483.35(h)(3)(iii). Further, feeding assistants must work
under the supervision of a registered, or licensed practical,
nurse and must call a supervisory nurse for assistance in the
case of an emergency. Id. § 483.35(h)(2). Finally, the rule
clarifies that feeding assistants are meant to supplement, not
supplant, nurse aides. 68 Fed. Reg. 55,529.

III.    District Court Proceedings

   Plaintiffs sought declaratory and injunctive relief in district
court, alleging that the regulations violated the Reform Law
and were arbitrary and capricious in violation of the Adminis-
trative Procedure Act. After dismissing six co-plaintiffs for
lack of standing, the district court granted summary judgment
to the Secretary, concluding that the Reform Law’s use of the
term “nursing or nursing-related services” was ambiguous,
that the agency’s interpretation of it a permissible construc-
tion which did not frustrate congressional intent, and that the
agency’s action was not arbitrary or capricious.

  Plaintiffs timely appealed, contesting only the district
court’s determination that the regulations do not violate the
Reform Law.
         RESIDENT COUNCILS OF WASHINGTON v. LEAVITT       11093
                STANDARD OF REVIEW

  We review a district court’s grant of summary judgment de
novo. CreAgri, Inc. v. USANA Health Scis., Inc., 474 F.3d
626, 629 (9th Cir. 2007).

   “When reviewing an agency’s construction of a statute it is
charged with administering, we first look to the statutory text
to see whether Congress has spoken directly to the question
at hand. ‘If the intent of Congress is clear, that is the end of
the matter; for the court, as well as the agency, must give
effect to the unambiguously expressed intent of Congress.’ ”
Contract Mgmt., Inc. v. Rumsfeld, 434 F.3d 1145, 1146-47
(9th Cir. 2006) (per curiam) (quoting Chevron, U.S.A., Inc. v.
Natural Res. Def. Council, Inc., 467 U.S. 837, 842-43
(1984)). Thus, “[t]he language of a statute is controlling when
the meaning is plain and unambiguous.” United States v.
Maria-Gonzalez, 268 F.3d 664, 668 (9th Cir. 2001).

   If, however, the statute is uncertain or ambiguous with
respect to the specific issue, a reviewing court “cannot simply
impose [its] own construction.” See United States v. Lopez-
Perera, 438 F.3d 932, 935 (9th Cir. 2006). Rather, under
Chevron, we defer to the agency’s interpretation if it is based
on “a permissible construction of the statute.” 467 U.S. at
843.

                        DISCUSSION

   The sole issue before us is whether feeding nursing home
residents without complicated feeding problems constitutes a
“nursing or nursing-related service,” which must therefore be
performed by a certified nurse aide. The Secretary has deter-
mined that such activity is not a “nursing-related service” and
may therefore be performed by a “feeding assistant” subject
to fewer training requirements and less oversight than a nurse
aide. In evaluating the Secretary’s interpretation, we employ
the familiar two-step Chevron test.
11094      RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
I.    Chevron Step One: Unambiguous Meaning

     A)   Standard

   We must first determine whether the meaning of the
Reform Law is plain and unambiguous and, therefore, con-
trolling. See Maria-Gonzalez, 268 F.3d at 668. To determine
if Congress has directly spoken to the issue of whether feed-
ing nursing home residents without complicated feeding prob-
lems is a nursing or nursing-related activity, “we employ the
traditional tools of statutory construction; if Congress had an
intent on this issue, that intent is the law and must be given
effect.” Student Loan Fund of Idaho, Inc. v. U.S. Dep’t of
Educ., 272 F.3d 1155, 1165 (9th Cir. 2001) (internal quota-
tions omitted).

      These tools of construction require us first to engage
      in a textual analysis of the relevant statutory provi-
      sions and to read the words of statutes in their con-
      text and with a view to their place in the overall
      statutory scheme. If the proper interpretation is not
      clear from this textual analysis, the legislative his-
      tory offers valuable guidance and insight into Con-
      gressional intent. However, it is well established that
      legislative history which does not demonstrate a
      clear and certain congressional intent cannot form
      the basis for enjoining regulations.

Id. (citations and quotation marks omitted).

   In conducting this analysis, we may not rewrite a statute,
but instead simply “construe what Congress has written. After
all, Congress expresses its purpose by words. It is for us to
ascertain—neither to add nor to subtract, neither to delete nor
to distort.” 62 Cases, More or Less, Each Containing Six Jars
of Jam v. United States, 340 U.S. 593, 596 (1951). “[U]nless
otherwise defined, words will be interpreted as taking their
ordinary, contemporary, common meaning.” Wilderness Soc’y
             RESIDENT COUNCILS OF WASHINGTON v. LEAVITT             11095
v. U.S. Fish & Wildlife Serv., 353 F.3d 1051, 1060 (9th Cir.
2003) (en banc) (internal quotations omitted). If necessary to
discern Congress’s intent, we may look to “the structure and
purpose of a statute . . . in determining the plain meaning of
its provisions.” Id. If Congress has spoken directly to the
question at hand, we may not defer to a contrary agency inter-
pretation. Id. at 1061.

  B)       Analysis

   Although Plaintiffs acknowledge that the Reform Law nei-
ther expressly defines “nursing or nursing-related services,”
nor explicitly states that all resident feeding must be per-
formed by a certified nurse aide, they nonetheless contend
that the Reform Law’s plain language, general purpose, and
structure demonstrate that Congress clearly intended all resi-
dent feeding to be performed by certified nurse aides.

      1)    Plain Language

   [1] As noted above, the Reform Law prohibits the full-time
use of any individual performing “nursing or nursing-related
services to residents” for more than four months unless the
individual has completed a minimum of 75 hours of train-
ing. 42 U.S.C. §§ 1395i-3(b)(5)(A); 1395i-3(b)(5)(F); 1395i-
3(f)(2)(A)(i); 1396r(b)(5)(A); 1396r(b)(5)(F); 1396r(f)(2)
(A)(i). Congress provided no further elaboration on its intent
or the definitions of the relevant terms in the statutory text or
legislative history. See, e.g., H.R. Rep. 100-391(I), at 457,
930.

  Referencing dictionary definitions of “nursing” and “relat-
ed,”6 Plaintiffs contend that the statute’s meaning is clear:
  6
    Citing the Oxford English Dictionary, Second Edition, Plaintiffs define
“nursing” as “[t]he practice or profession of providing health care as a
nurse” and “related” as “[h]aving relation to, or relationship with, some-
thing else.”
11096    RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
They argue that the inclusion of “ ‘nursing-related [services]’
indicates that certification is required for the personal care
assistance that has a relation to the health care provided to
nursing home residents,” and they assert ipse dixit that such
assistance “includes assistance with eating, as well as assis-
tance with other activities of daily living such as dressing,
walking, and using the toilet.”

   No support is offered for this claim beyond the statement
that “residents live in nursing homes only because they cannot
live independently [and] . . . need substantial assistance to
perform daily tasks such as dressing, walking, eating, and
using the toilet.” True as this might be in most cases, it fails
to account for the regulations’ limited application to residents
without complicated feeding problems. All agree that feeding
the most infirm or medically challenging residents constitutes
“nursing-related activity” and requires a nurse aide.

   The next argument is that the statute’s plain language
clearly “demonstrate[s] a decision by Congress to require that
all hands-on care by nursing home staff members be provided
exclusively by licensed health professionals, registered dieti-
cians, or [certified nurse aides].” Again, little support is
offered. Although a congressional committee has noted that
“nurse aides provide most of the ‘hands-on’ care to nursing
faclity [sic] residents,” H.R. Rep. 101-247, at 459 (1989),
reprinted in 1989 U.S.C.C.A.N. 1906, 2185, and the Secretary
has described nurse aides as “performing tasks on an individ-
ual,” in “direct contact with a resident,” and “directly
involved in patient care,” 42 C.F.R. § 483.152(a)(3), (b)(1);
56 Fed. Reg. at 48,890, it simply does not follow that nurse
aides must perform all hands-on care of nursing home resi-
dents. At most, these statements indicate that all work per-
formed by nurse aides is “hands-on.” They do not, however,
support the converse—i.e., that all hands-on work must be
performed by nurse aides.

   [2] In sum, nothing in the statutory language or legislative
history clearly shows that Congress intended the phrase
              RESIDENT COUNCILS OF WASHINGTON v. LEAVITT   11097
“nursing-related services” to include all resident feeding or
that all hands-on care be performed by nurse aides. Unable to
identify Congress’s clear intent from the plain language, we
turn to the purpose and structure of the statute.

    2)        Purpose and Structure

         a)     Purpose

   Plaintiffs note that because the Reform Law is remedial in
nature it should therefore be construed broadly in light of its
purpose. See Tcherepnin v. Knight, 389 U.S. 332, 336 (1967)
(noting the “familiar canon of statutory construction that
remedial legislation should be construed broadly to effectuate
its purposes”). Plaintiffs contend that the Reform Law’s pur-
pose and structure indicates that the phrase “nursing or
nursing-related services” “includes virtually all hands-on care
provided in a nursing home.”

   [3] All agree that the “central purpose” of the Reform Law
was “to improve the quality of care for Medicaid-eligible
nursing home residents.” H.R. Rep. No. 100-391(I) at 452.
Plaintiffs argue this purpose was to be served “in large part
through the nurse aide certification standards,” which must
therefore “apply broadly to all staff members providing
hands-on assistance with activities of daily living.” Once
again, no support is offered for the assertion that Congress
intended “all hands-on care” to be performed by nurse aides.
True as it may be that nurse aide certification plays an impor-
tant part in Congress’s efforts to improve nursing home care
via the Reform Law, this says nothing about whether the feed-
ing of residents without complicated feeding problems consti-
tutes a “nursing-related service” that Congress intended to
address through nurse aide certification.

   [4] In sum, as the district court held, congressional intent
that resident feeding constitutes a nursing-related service can-
11098        RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
not be gleaned from the Reform Law’s general purpose to
improve nursing home care.

        b)    Structure

   [5] We next address whether the Reform Law’s structure—
explicitly delegating specific tasks to the Secretary—
demonstrates that Congress did not intend to delegate the task
of defining “nursing or nursing-related services.” Plaintiffs
note, for example, that the Reform Law specifies that the Sec-
retary should define “serious mental illness” and “specialized
services.” See 42 U.S.C. § 1396r(e)(7)(G)(i), (iii). While true
that definition of certain terms was expressly left to the Secre-
tary’s discretion, there is nothing to indicate Congress
intended to prohibit the Secretary from defining other terms—
especially where the terms were otherwise left undefined by
the Reform Law. It strains credulity to accept the argument
that the Secretary may only define terms when expressly
authorized to do so by Congress, given that Congress made no
attempt to define the generic, yet vital, phrase “nursing or
nursing-related services.”

   Chevron itself acknowledges the possibility of implicit del-
egation to the agency where the statute is silent. 467 U.S. at
843-44. Further, the Secretary undeniably has general rule-
making authority, 42 U.S.C. §§ 1302, 1395hh(a)(1), as well as
specific rulemaking authority with respect to nursing homes,
id. §§ 1395i-3(f), 1396r(f), and we have regularly applied
Chevron deference to agency interpretations of the Medicare
and Medicaid statutes, see, e.g., Alaska Dep’t of Health &
Soc. Servs. v. Ctrs. for Medicare & Medicaid Servs., 424 F.3d
931, 938-39 (9th Cir. 2005).

   In addition, contrary to Plaintiffs’ contention, the Secre-
tary’s claimed discretion to define “nursing-related services”
is not “virtually unchecked.” There are certain activities that
so clearly fall within the ambit of “nursing-related services”
that the Secretary would not be able to reasonably remove
            RESIDENT COUNCILS OF WASHINGTON v. LEAVITT                 11099
them from the definition by regulation. However, feeding res-
idents without complicated feeding problems does not fit so
clearly within the plain meaning of “nursing related”; and it
is such borderline activities over which the Secretary has dis-
cretion. To hold otherwise, and conclude that the Secretary
lacked discretion to define “nursing-related services,” would
be to leave a critical statutory term incurably vague, frustrat-
ing the purpose and effectiveness of the Reform Law.

   Plaintiffs’ final argument—that even if the Secretary has
discretion to define “nursing or nursing-related services,”
Congress did not intend the definition to change based on
employment conditions and therefore the current nationwide
nurse aide shortage reported by the Secretary cannot justify a
changed definition—is also ultimately unpersuasive.7

   [6] Although the Secretary’s examination of the definition
of “nursing-related services” appears to have been prompted
by changed market conditions, the regulations are the result
of the Secretary’s subsequent conclusion that feeding resi-
dents without complicated feeding problems did not constitute
a “nursing-related service”—a determination that was made
based on the nature of the activity in question. The nurse aide
shortage was relevant only insofar as it prompted the Secre-
tary to reevaluate the regulations in order to ensure the best
care possible was being provided to nursing home residents.8
  7
     Plaintiffs are likely correct that market conditions should not control an
agency’s statutory interpretation. See 56 Fed. Reg. at 48884-85 (rejecting
a suggestion to allow a waiver of training requirements for facilities
unable to attract enough nurse aides).
   8
     Because the nurse aide shortage was not why the Secretary determined
that feeding residents without complicated feeding problems was a non-
nursing-related service, Plaintiffs’ argument that the Reform Law
expressly provides for waiver of nurse requirements in case of staff short-
age, but does not do so for nurse aides, is irrelevant. See 42 U.S.C.
§ 1395i-3(b)(4)(C)(i)-(ii). The current regulation does not waive nurse
aide requirements. Rather, it specifies that certain services previously
assumed to be “nursing-related” are not and thus need not be performed
by nurse aides. Nursing homes must continue to meet the various nurse
aide requirements; the current regulations simply clarify that feeding resi-
dents without complicated feeding problems is not a “nursing-related ser-
vice.”
11100       RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
      3)    Conclusion

   Congress did not define the phrase “nursing or nursing-
related service” in either the Reform Law or its legislative his-
tory. Neither did it state that all hands-on care (or all feeding
tasks) must be performed by nurse aides. Nor can such an
intent be derived from the statute’s general purpose or struc-
ture. Accordingly, Congress did not speak directly to the
question at hand and our analysis must turn to Chevron’s sec-
ond step to determine whether the Secretary’s interpretation
was a permissible construction of the statute.

II.    Chevron Step Two: Agency Deference

  A)       Standard

   “When relevant statutes are silent on the salient question,
we assume that Congress has implicitly left a void for an
agency to fill . . . . [and] must therefore defer to the agency’s
construction of its governing statutes, unless that construction
is unreasonable.” Ass’n of Pub. Agency Customers, Inc. v.
Bonneville Power Admin., 126 F.3d 1158, 1169 (9th Cir.
1997) (citing Chevron, 467 U.S. at 843-44). Where “the court
determines Congress has not directly addressed the precise
question at issue, [it] does not simply impose its own con-
struction on the statute.” Chevron, 467 U.S. at 843. Rather,
we examine only “whether the agency’s answer is based on
a permissible construction of the statute.” Id. “This test is sat-
isfied if the agency’s interpretation ‘reflects a plausible con-
struction of the statute’s plain language and does not
otherwise conflict with Congress’ expressed intent.’ ” Or.
Trollers Ass’n v. Gutierrez, 452 F.3d 1104, 1116 (9th Cir.
2006), cert. denied, 127 S. Ct. 2028 (2007) (quoting Rust v.
Sullivan, 500 U.S. 173, 183 (1991)). In other words, “[s]o
long as the agency’s construction is reasonably consistent
with the statute, we defer to it.” Id.
           RESIDENT COUNCILS OF WASHINGTON v. LEAVITT       11101
  B)     Analysis

   Three primary challenges are made to the Secretary’s inter-
pretation: (1) the use of feeding assistants will result in
reduced care for nursing home residents; (2) because nurse
aide training is currently inadequate, further reducing staff
training requirements frustrates congressional intent; and (3)
the agency’s interpretation is not entitled to deference because
it did not adequately explain its change in policy.

    1)    Reduced Level of Care

   No support is offered for this claim. The contention is that
(1) feeding assistants, though limited by regulation to feeding
residents without complicated feeding problems, will none-
theless “perform tasks for which they are not trained,” and (2)
“residents may find themselves monitored by direct-care
employees who are trained to do no more than provide mini-
mal assistance with relatively trivial feeding assistance tasks.”

   [7] The first argument fails because speculation that feed-
ing assistants may exceed their authority under the regulations
cannot be a basis for concluding the regulations run afoul of
the statute. To hold otherwise would render every regulation
an impermissible statutory construction because every regula-
tion can be violated.

   [8] The second claim is equally unpersuasive. Aside from
acknowledging that feeding assistants will be performing only
“relatively trivial feeding assistance tasks,” it fails to identify
how resident monitoring during feeding by such individuals
violates the statute. Nursing homes employing feeding assis-
tants would still be required to adhere to the other regulatory
requirements pertaining to resident care and supervision.
Feeding assistants are permitted only to supplement, not
replace, nurse aides and other professionals. See 68 Fed. Reg.
at 55,529.
11102      RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
   Furthermore, as a general matter, there is no evidence of
record to suggest that the use of feeding assistants to feed res-
idents without complicated feeding problems will operate to
reduce the level of care for nursing home residents. To the
contrary, feeding assistant programs in two states have
yielded positive results. Id. at 55,529-30. Further, in response
to public commenters’ concerns, the agency modified the reg-
ulations to, inter alia, provide examples of conditions that
preclude the use of a feeding assistant, require training prior
to feeding residents, and require a more frequent assessment
by a nurse of a resident’s eligibility for feeding by a feeding
assistant. Id. at 55,531-32, 55,534, 55,536.

   There can be little debate that a shortage of nurse aides has
led to a reduced level of care for all nursing home residents.
Common sense dictates that easing the burden on nurse aides
by delegating non-nursing-related tasks to other workers will
enable nurse aides to devote their attention to tasks more
important and more difficult than the “relatively trivial feed-
ing tasks” they were previously saddled with. Plaintiffs’
untethered speculation that the regulations will result in a
diminished level of care for nursing home residents is insuffi-
cient to demonstrate that the Secretary’s interpretation of the
Reform Law was unreasonable.9
  9
    The related argument that permitting paid feeding assistants will lead
to a proliferation of other single-task workers, resulting in reduced care for
nursing home residents, is also unpersuasive. We are asked to review only
the Secretary’s decision that feeding residents without complicated feed-
ing problems does not constitute a “nursing-related service” and therefore
can be performed by a paid feeding assistant. Should the Secretary subse-
quently decide that other services are similarly not “nursing-related,” we
may ultimately be asked to determine the reasonableness of such deci-
sions. But that is not the case before us. To conclude that a reasonable
construction of a statute in this case is impermissible based solely on the
possibility that the Secretary may later use our decision to attempt to jus-
tify an unreasonable interpretation of the statute would be to eschew our
current judicial responsibilities.
         RESIDENT COUNCILS OF WASHINGTON v. LEAVITT        11103
    2)   Inadequate Nurse Aide Training

   Plaintiffs further contend that the unreasonableness of the
Secretary’s interpretation permitting the use of feeding assis-
tants is especially pronounced because the required training of
nurse aides has “not kept pace with nursing home industry
needs,” presumably suggesting that the Secretary should be
increasing training requirements, rather than reducing them
for certain tasks. The alleged inadequacy of nurse aide train-
ing generally is irrelevant to this court’s inquiry as to whether
the agency’s feeding assistant regulations frustrate congres-
sional intent.

    3)   The Secretary’s Explanation of HHS’s Change in
         Policy

   “An agency interpretation of a relevant provision which
conflicts with the agency’s earlier interpretation is entitled to
considerably less deference than a consistently held agency
view.” INS v. Cardoza-Fonseca, 480 U.S. 421, 446 n.30
(1987) (internal quotations omitted). This court has held that
an agency’s “new” position is entitled to deference “so long
as the agency acknowledges and explains the departure from
its prior views.” Seldovia Native Ass’n v. Lujan, 904 F.2d
1335, 1346 (9th Cir. 1990) (internal quotations omitted).
However, “[a]n initial agency interpretation is not instantly
carved in stone,” but rather “the agency . . . must consider
varying interpretations and the wisdom of its policy on a con-
tinuing basis.” Chevron, 467 U.S. at 863-64. To that end, an
agency “must be given ample latitude to adapt its rules and
policies to the demands of changing circumstances.” Rust,
500 U.S. at 186-87 (internal quotations omitted).

   The Secretary acknowledged that the new regulations con-
stituted a policy change in the preambles to both the proposed
and final rules. 67 Fed. Reg. at 15,150-51; 68 Fed. Reg. at
55,528-29. The Secretary explained that changed circum-
stances in the nursing home industry—i.e., a shortage of nurse
11104    RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
aides and a higher percentage of nursing home residents who
require a greater level of care—necessitated a reexamination
of the agency’s prior opinion that all resident feeding must be
performed by a nurse aide. 68 Fed. Reg. at 55,529-30. The
Secretary noted that some residents require only minimal
assistance during mealtimes and that such assistance does not
require nursing training. Id. By nonetheless requiring that
nurse aides feed such residents, the Secretary concluded that
the realities of the nursing home industry meant that those res-
idents without complicated feeding problems were receiving
little or no assistance at mealtimes and that nurse aide atten-
tion was being diverted from those residents who needed it
most. Id.

   [9] The Secretary ultimately concluded that employing
feeding assistants, specially trained in feeding techniques and
elder care, to feed those residents without complicated feed-
ing problems would free the nurse aides to focus their atten-
tion on the more difficult patients, while also ensuring that
residents with minimal problems receive adequate attention,
resulting in better care for all. Id. Although the agency did not
specifically state why it had changed its interpretation of
“nursing-related services” to exclude feeding of residents
without complicated feeding problems, it did note that it did
“not consider the kinds of tasks facilities may ask feeding
assistants to provide [to be] either nursing or nursing related.”
Id. at 55,530-31. In response to comments, the agency further
noted:

    While feeding has been part of the nurse aide train-
    ing curriculum, that requirement was predicated on
    the nurse aide having to tend to persons with pro-
    nounced eating complications (such as swallowing
    disorders) for which specialized training is essential.
    What facilities would be free to do as a result of this
    rule, however, is to use persons who have had a
    lesser level of training to assist residents who have
    no feeding issues that require any specialized atten-
            RESIDENT COUNCILS OF WASHINGTON v. LEAVITT                 11105
     tion. Thus, we do not consider feeding assistants
     who may be used by facilities under this rule to be
     engaged in nursing or nursing related activities.

Id. at 55,531. This explanation clearly reveals the agency’s
reasoning in determining that feeding residents without com-
plicated feeding problems does not constitute a nursing-
related service.

   Further, as noted above, “nursing-related services” has not
been previously defined by statute or regulation.10 As such,
the agency’s change in policy with the current rule is only a
change insofar as it diverges from past interpretations in
informal letters by agency administrators. Such pronounce-
ments, of course, “lack the force of law,” Christensen v. Har-
ris County, 529 U.S. 576, 587 (2000), and are entitled to
respect only insofar as they have the “power to persuade,”
which is a function of “the thoroughness evident in [their]
consideration” and “the validity of [their] reasoning.” Skid-
more v. Swift & Co., 323 U.S. 134, 140 (1944). Here, the
agency letters offer virtually no evidence or reasoning in sup-
port of their conclusions, but simply state that nurse aides
must perform feeding tasks. If reviewing courts accord less
deference to informal agency pronouncements, it logically
follows that the agency itself is also entitled to give prior
informal interpretations less deference, permitting it to change
   10
      As Plaintiffs note, the Secretary has stated by formal rule that individ-
uals providing “nursing or nursing-related services” must meet the nurse
aide requirements “regardless of . . . the scope of services provided.” 56
Fed. Reg. at 48,890. However, this statement was made as part of the Sec-
retary’s response to a request to further define “nurse aide” and does not
purport to be a definition of “nursing-related services.” See id. Quite the
contrary, the Secretary expressly declined to refine the definition of
“nursing-related services.” See id. The new rule does not alter the Secre-
tary’s conclusion that anyone performing nursing-related services, regard-
less of their scope, must meet the nurse aide requirements. Rather, the new
rule determines that a certain activity—feeding residents without compli-
cated feeding problems—does not constitute a “nursing-related service.”
11106       RESIDENT COUNCILS OF WASHINGTON v. LEAVITT
course when both necessary and consistent with the governing
statute.

   The letters in question, though they address resident feed-
ing generally, do not specifically answer whether feeding resi-
dents without complicated feeding problems—the sole focus
of the new rule—constitutes a “nursing-related service.” In
this sense, the Secretary’s current interpretation is less a break
with the past than a refinement of it. The current regulations
are the first agency statement to address the precise question
at issue—whether feeding residents without complicated feed-
ing problems is a “nursing-related service”—and are the only
examination of nursing home feeding practices and statutory
definitions to be supported by evidence and analysis.11

       4)   Conclusion

   [10] The Secretary’s interpretation of the undefined statu-
tory phrase “nursing or nursing-related services” to exclude
feeding of nursing home residents without complicated feed-
ing problems is a permissible construction of the statute. The
Secretary reasonably concluded that such services do not
necessitate the extensive training required of nurse aides and
that permitting trained feeding assistants to assume such tasks
would advance the overall goals of the Reform Law in light
of changing circumstances in the nursing home industry. In
this respect, the Secretary’s construction is “reasonably con-
sistent with the statute” and is accordingly entitled to defer-
ence. See Or. Trollers, 452 F.3d at 1116.
  11
     Plaintiffs’ additional objection that “the phrase ‘nursing or nursing-
related’ was understandable and enforceable from 1991 through 2001, but
suddenly ambiguous in 2002” is baseless. The Secretary has never sug-
gested that the phrase “nursing or nursing-related” is unambiguous. To the
contrary, since the first regulations issued under the Reform Law, the
scope of the term has been debated and questioned as demonstrated by
public comments seeking clarification, 56 Fed. Reg. at 48,890, and the let-
ters in the record responding to such inquiries.
          RESIDENT COUNCILS OF WASHINGTON v. LEAVITT       11107
                        CONCLUSION

   [11] Congress has not “spoken directly to the question at
hand,” insofar as the Reform Law neither defines “nursing or
nursing-related services,” nor specifically states that all feed-
ing tasks (or all hands-on care) must be performed by certified
nurse aides. Neither can such an intent be gleaned from the
legislative history or the Reform Law’s general purpose or
structure. Plaintiffs are unable to establish that the Secretary’s
interpretation of the phrase to exclude the feeding of nursing
home residents without complicated feeding problems will
frustrate congressional intent or is otherwise inconsistent with
the Reform Law. As such, the Secretary’s permissible con-
struction of the statute is entitled to deference.

  AFFIRMED.
