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VANGUARD/(R)/ PRIMECAP FUND


SUPPLEMENT TO THE PROSPECTUS


IMPORTANT CHANGES TO VANGUARD PRIMECAP FUND
New or current Vanguard PRIMECAP Fund shareholders may not open new accounts or
contribute to existing Fund accounts, except as described in this supplement.
Clients enrolled in Flagship Services(TM) may open new Fund accounts, without
purchase limitations, in individual, joint, and/or personal trust registrations.
There is no specific time frame for when the Fund will reopen, or increase
investment limitations, for other Vanguard clients.

LIMITS ON ADDITIONAL INVESTMENTS

Current PRIMECAP Fund shareholders may invest up to $25,000 per year in the
Fund. The $25,000 limit does not apply to Fund shareholders enrolled in Flagship
Services. Where applicable, the $25,000 limit includes the total amount invested
during any calendar year in each Fund account registered to the same primary
Social Security or taxpayer identification number. Dividend and capital gains
reinvestments do not count toward the $25,000 annual limit. Participants in
certain qualified retirement plans may continue to invest in accordance with the
terms of their plans. Certain qualifying asset allocation programs may continue
to operate in accordance with the program terms.

Vanguard PRIMECAP Fund may modify these transaction policies at any time without
prior notice to shareholders.

You may call Vanguard for more detailed information about the Fund's transaction
policies. Investors in nonretirement accounts and IRAs may call Vanguard's
Investor Information Department at 800-662-7447. Participants in
employer-sponsored retirement plans may call Vanguard Participant Services at
800-523-1188.








(C)2007 The Vanguard Group, Inc. All rights reserved.
Vanguard Marketing Corporation, Distributor.                      PSFR59 092007