[SHIP LOGO/(R)/]
                            [THE VANGUARD GROUP/(R)/ LOGO]

             VANGUARD(R) PRIMECAP FUND SUPPLEMENT TO THE PROSPECTUS

IMPORTANT CHANGES TO VANGUARD PRIMECAP FUND

FUND CLOSED TO NEW SHAREHOLDERS
Effective as of the close of business on March 4, 2004, Vanguard PRIMECAP Fund
stopped accepting new shareholders, and set limits on additional investments by
existing shareholders as further described below. There is no specific time
frame for when the Fund will reopen.

Existing shareholders of Vanguard PRIMECAP Fund may invest up to $25,000 per
year in the Fund during the closed period. This $25,000 limit applies to the
total amount invested during any calendar year in all Fund accounts 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 their program terms.

ELECTRONIC TRANSACTIONS
During the closed period,  it will not be possible to purchase Vanguard PRIMECAP
Fund  shares   through   Vanguard's   website  or   Tele-Account/(R)/   service.
Shareholders, however, may continue to redeem Fund shares using these electronic
methods.

Vanguard PRIMECAP Fund may modify these transaction policies at any time without
advance notice to shareholders. Please call Vanguard for more detailed
information about the Fund's transaction policies. Investors in nonretirement
accounts and IRAs should call Vanguard's Investor Information Department at
1-800-662-7447. Participants in employer-sponsored retirement plans should call
Vanguard/(R)/ Participant Services at 1-800-523-1188.




(C)2005 The Vanguard Group, Inc. All rights reserved.
Vanguard Marketing Corporation, Distributor.                      PSa59 012005