SHIP LOGO  VANGUARD/(R)/
                                                                   P.O. Box 2600
                                                     Valley Forge, PA 19482-2600

                                                                    610-669-1538
                                                      Judy_L_Gaines@vanguard.com

April 17, 2006


Christian Sandoe, Esq.
Division of Investment Management
U.S. Securities and Exchange Commission                   via electronic filing
450 Fifth Street,
N.W., Fifth Floor
Washington, D.C. 20549

RE:      Vanguard Quantitative Funds


Dear Mr. Sandoe,

         The following responds to your comments of April 10, 2006 on the
post-effective amendment of the registration statement of the above-referenced
registrant. You commented on Post-Effective Amendment No. 25 that was filed on
February 22, 2006.


Comment 1:        Prospectus - Primary Risks
- --------------------------------------------
Comment:          Replace references to small-cap risk with that of large-cap
                  risk.

Response:         We will make the requested revision.

Comment 2:        Prospectus - Performance/Risk Information
- -----------------------------------------------------------
Comment:          Remove the sentence that points an investor toward the
                  Supplemental Performance Information section of the
                  prospectus for more information.

Response:         We have considered the comment and plan to keep a modified
                  version of the sentence in this section. General Instruction
                  C.2.(a) of Form N-1A says "cross-references with the
                  prospectus are most useful when their use assists investors in
                  understanding the information presented and does not add
                  complexity to the prospectus." In keeping with the spirit of
                  this instruction, we think that it benefits an investor
                  looking at the Item 2 disclosure to know that farther back in
                  the prospectus there is related information. However, it is
                  not our intention to mislead an investor into thinking that
                  the information in the back of the prospectus is performance
                  of this Fund.

                  Accordingly, we will amend the sentence to read, "Please refer
                  to the Performance of a Different but Similar Investment
                  Vehicle section of this prospectus for information on the
                  performance of a different but similar investment vehicle."



Christian Sandoe, Esq.
April 17, 2006
Page 2

Comment 3:        Prospectus - Security Selection
- -------------------------------------------------
Comment:          Include the capitalization range within which the Fund will
                  invest.

Response:         We will add the requested disclosure.

Comment 4:        Prospectus - Market-Timing
- --------------------------------------------
Comment:          Each Fund's broad policies with respect to frequent trading
                  and market-timing are disclosed under the heading "Frequent
                  Trading or Market-Timing." However, specific policies
                  applicable to discrete types of investors are disclosed in
                  various places throughout the "Investing with Vanguard"
                  section. All of each Fund's policies concerning frequent
                  trading and market-timing should be disclosed together under
                  the heading "Frequent Trading and Market-Timing."

Response:         We believe that each Fund's policies against frequent trading
                  and market-timing are properly disclosed in the prospectus
                  pursuant to Item 6(e)(4) of Form N-1A. Item 6(e)(4) does not
                  require that the specific policies applicable to each type of
                  shareholder be disclosed together in the prospectus. As such,
                  we believe that it is appropriate to have the general
                  discussion of each Fund's policies against frequent trading
                  and market-timing under the heading "Frequent Trading or
                  Market-Timing" with a reference to the "Investing with
                  Vanguard" section where specific policies applicable to
                  different types of shareholders and transactions are
                  disclosed.

                  We believe that removing the disclosure from the "Investing
                  with Vanguard" section and combining the disclosure into a
                  single "Frequent Trading and Market-Timing" section would make
                  the discussion of transaction policies incomplete in the
                  "Investing with Vanguard" section. Repeating the specific
                  policies in both the "Investing with Vanguard" section and
                  under the "Frequent Trading and Market-Timing" heading would
                  unnecessarily clutter the prospectus with duplicative
                  disclosure.

Comment 5:        Prospectus - Investment Advisor
- -------------------------------------------------
Comment:          Please include disclosure directing investors where to look
                  for a discussion on why the board of trustees approved the
                  Fund's advisory agreement.

Response:         We will make the requested revision.

Comment 6:        Prospectus - Plain Talk About the Fund's Portfolio Manager
- ----------------------------------------------------------------------------
Comment:          Please clarify the PM's experience over the past 5 years.

Response:         We will make the requested revision.

Comment 7:        Prospectus - Supplemental Performance Information
- -------------------------------------------------------------------
Comment:          Please revise the heading of this section to clarify that the
                  performance shown is not that of this Fund.


Christian Sandoe, Esq.
April 17, 2006
Page 3

Response:         We will change the heading of this section to "Performance of
                  a Different but Similar Investment Vehicle."

Comment 8:        Prospectus - Supplemental Performance Information
- -------------------------------------------------------------------
Comment:          Clarify what is meant by "an affiliate" of the Fund's adviser
                  manages an "entity..." and disclose that the comparable
                  entity's investment policies are identical to those of the
                  Fund.

Response:         We will make the requested clarification and revisions.

Comment 9:        Prospectus - Supplemental Performance Information
- -------------------------------------------------------------------
Comment:          In the second paragraph beneath this heading, reverse the
                  order of the discussion.  Rather than discussing the Fund
                  and how it differs from the Trust, start with the Trust, and
                  discuss how it differs from the Fund.

Response:         We will make the requested revisions.

Comment 10:       Prospectus - Supplemental Performance Information
- -------------------------------------------------------------------
Comment:          In disclosing supplemental performance in reliance on
                  Nicholas-Applegate, a Fund must show the composite performance
                  of all of an adviser's accounts that are managed with
                  investment objectives, policies, and strategies substantially
                  similar to those used in managing the Fund.

Response:         Our disclosure complies with this requirement. We have only
                  shown performance of the Structured Large Cap Equity Trust
                  because that is the only entity of any sort (RIC, separate
                  account, commingled trust) that Vanguard manages that has
                  investment objectives, policies, and strategies that are
                  similar to that of the Fund. There are no other entities whose
                  inclusion would be appropriate in this section.

Comment 11:       SAI - Investment Policies
- -------------------------------------------
Comment:          Revise the 80% policy for the Fund to reference large-cap
                  stocks.

Response:         We will make the requested revision.

Comment 12:       SAI - Investment Advisor
- ------------------------------------------
Comment:          The detail regarding the Fund's advisory fee structure (base
                  and performance fee structure) should be included in the SAI.

Response:         We do not plan to include this information in the SAI for this
                  Fund or in other the SAIs of our other registrants.

                  Vanguard operates a multi-manager structure for certain funds
                  pursuant to an exemptive order granted by the Commission in
                  2003 (the "2003 Order").(1) The funds are permitted under the
                  2003 Order to enter into and amend investment advisory
                  agreements with unaffiliated third-party advisors without
                  shareholder approval, provided certain conditions are met. The
                  2003

(1) In the Matter of Vanguard Convertible Securities Fund, et al., File No.
    812-12380, Inv. Co. Act Release Nos. 26062 (May 29, 2003) (Notice) and 26089
    (June 25, 2003) (order).



Christian Sandoe, Esq.
April 17, 2006
Page 4

                  Order exempts multi-managed Vanguard funds from certain
                  disclosure requirements so that they are only required to
                  disclose advisory fees (as both a dollar amount and as a
                  percentage of a fund's net assets) as follows: (1) aggregate
                  fees paid by a fund to Vanguard and any affiliated advisors;
                  (2) aggregate fees paid by the fund to unaffiliated
                  third-party advisors; and (3) aggregate fees paid by the fund
                  to all investment advisors (collectively, the "Aggregate Fee
                  Disclosure"). A fund using Aggregate Fee Disclosure does not
                  have to include additional details, including asset-based and
                  performance fee schedules, about its advisory fees and fee
                  arrangements.

                  An Aggregate Fee Disclosure regime is in the best interests of
                  Fund shareholders. In a recent proposal to codify
                  multi-manager exemptive orders, the Commission said that fund
                  sponsors (including Vanguard) have represented that they "are
                  able to negotiate lower fees with subadvisers if they do not
                  have to disclose those fees separately, and in our orders we
                  have provided them relief from our disclosure requirements. We
                  are proposing to codify this relief, which permits a manager
                  of managers fund to disclose only the aggregate amount of
                  advisory fees that it pays to subadvisers as a group."(2)

Comment 13:       SAI - Material Conflicts of Interest
- ------------------------------------------------------
Comment:          Please describe what Franklin Portfolio Associates considers
                  to be material conflicts of interest.

Response:         We will make the requested revisions.

Comment 14:       SAI - Description of Compensation
- ---------------------------------------------------
Comment:          Please expand on the discussion of Franklin Portfolio
                  Associates by specifying what peer groups and benchmarks it is
                  compared to in determining compensation.

Response:         We will make the requested revisions.

Comment 15:       SAI - Ownership of Securities
- -----------------------------------------------
Comment:          Disclose Mr. Troyer's ownership of shares of the Structured
                  Large-Cap Equity Fund.

Response:         The Fund has not yet commenced operation, but we will disclose
                  that Mr. Troyer owns no shares.

Comment 16:       Tandy Requirements
- ------------------------------------
Comment:          The SEC is now requiring all registrants to provide at the end
                  of response letters to registration statement comments, the
                  following statements:
                  o The Fund is responsible for the adequacy and accuracy of the
                    disclosure in the filing.
                  o Staff comments or changes in response to staff comments in
                    the filings reviewed by the staff do not foreclose the
                    Commission from taking any action with respect to the
                    filing.
                  o The Fund may not assert staff comments as a defense in any
                    proceeding initiated by the Commission or any person under
                    the federal securities laws of the United States.

(2) Exemption from Shareholder Approval for Certain Subadvisory Contracts,
    Securities Act Release No. 8312 (Oct. 23, 2003).



Christian Sandoe, Esq.
April 17, 2006
Page 5

Response:         As required by the SEC, we will provide the foregoing
                  acknowledgements.

                                    * * * * *

                  As required by the SEC, the Fund acknowledges that:

                  o The Fund is responsible for the adequacy and accuracy of the
                    disclosure in the filing.
                  o Staff comments or changes in response to staff comments in
                    the filings reviewed by the staff do not foreclose the
                    Commission from taking any action with respect to the
                    filing.
                  o The Fund may not assert staff comments as a defense in any
                    proceeding initiated by the Commission or any person under
                    the federal securities laws of the United States.


         Please contact me at (610) 669-1538 with any questions or comments
regarding the above responses. Thank you.

Sincerely,


Judith L. Gaines
Associate Counsel
Securities Regulation, Legal Department