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Vanguard Federal Money Market Fund

Supplement to the Prospectus and Summary Prospectus

Important Note Regarding Vanguard Federal Money Market Fund

Vanguard Federal Money Market Fund (the Fund) will no longer open new accounts for individual investors, and it will no longer be available as a new investment option for defined contribution plans. In addition, the Fund will no longer open new accounts for, or accept additional investments from, any financial advisor, intermediary, or institutional investors. There is no specific time frame for when the fund will reopen.

During the Fund’s closed period, current retail shareholders may continue to purchase, exchange, or redeem shares of the Fund online, by telephone, or by mail.

The Fund may modify these transaction policies at any time and without prior notice to shareholders. You may call Vanguard for more detailed information about the Fund’s transaction policies. Participants in employer-sponsored plans may call Vanguard Participant Services at 800-523-1188. Investors in nonretirement accounts and IRAs may call Vanguard’s Investor Information Department at 800-662-7447.


© 2010 The Vanguard Group, Inc. All rights reserved.
Vanguard Marketing Corporation, Distributor.	PS 33 122010

Vanguard Federal Money Market Fund

Summary Prospectus

December 23, 2010

Investor Shares

Vanguard Federal Money Market Fund Investor Shares (VMFXX)

The Fund’s statutory Prospectus and Statement of Additional Information dated

December 23, 2010, and financial highlights information from the most recent

shareholder report are incorporated into and made part of this Summary

Prospectus by reference.

Before you invest, you may want to review the Fund’s Prospectus, which

contains more information about the Fund and its risks. You can find

the Fund’s Prospectus and other information about the Fund online at

www.vanguard.com/prospectus. You can also get this information at no

cost by calling 800-662-7447 or by sending an e-mail request to

online@vanguard.com.

The Securities and Exchange Commission has not approved or disapproved these securities or passed

upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Vanguard Federal Money Market Fund

Investment Objective
The Fund seeks to provide current income while maintaining liquidity and a stable share price of $1.

Fees and Expenses
The following tables describe the fees and expenses you may pay if you buy and hold shares of the Fund.

Shareholder Fees
(Fees paid directly from your investment)


Sales Charge (Load) Imposed on Purchase	None
Purchase Fee	None
Sales Charge (Load) Imposed on Reinvested Dividends	None
Redemption Fee	None
Account Service Fee (for fund account balances below $10,000)	$20/year

Annual Fund Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment)


Management Expenses	0.18%
12b-1 Distribution Fee	None
Other Expenses	0.04%
Total Annual Fund Operating Expenses	0.22%¹

1 Vanguard and the Fund's Board have voluntarily agreed to temporarily limit certain net operating expenses in excess of the Fund's daily yield so as to maintain a zero or positive yield for the Fund. Vanguard and the Fund's Board may terminate the temporary expense limitation at any time.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in the Fund’s shares. This example assumes that the Fund provides a return of 5% a year and that operating expenses remain as stated in the preceding table. The results apply whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


1 Year	3 Years	5 Years	10 Years
$23	$71	$124	$280

Primary Investment Policies
The Fund invests primarily in high-quality, short-term money market instruments. At least 80% of the Fund’s assets are invested in securities issued by the U.S. government and its agencies and instrumentalities. Although these securities are high-quality, most of the securities held by the Fund are neither guaranteed by the U.S. Treasury nor supported by the full faith and credit of the U.S. government. To be considered high-quality, a security generally must be rated in one of the two highest credit-quality categories for short-term securities by at least two nationally recognized rating services (or by one, if only one rating service has rated the security). The Fund maintains a dollar-weighted average maturity of 60 days or less and a dollar-weighted average life of 120 days or less.

Primary Risks
The Fund is designed for investors with a low tolerance for risk; however, the Fund’s performance could be hurt by:

• Income risk, which is the chance that the Fund’s income will decline because of falling interest rates. Because the Fund’s income is based on short-term interest rates—which can fluctuate significantly over short periods—income risk is expected to be high.

• Manager risk, which is the chance that poor security selection will cause the Fund to underperform relevant benchmarks or other funds with a similar investment objective.

• Credit risk, which is the chance that the issuer of a security will fail to pay interest and principal in a timely manner, or that negative perceptions of the issuer’s ability to make such payments will cause the price of that security to decline. Credit risk should be very low for the Fund, because it invests primarily in securities that are considered to be of high quality.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1 per share, it is possible to lose money by investing in the Fund.

Annual Total Returns
The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns compare with those of a relevant market index and a comparative benchmark. Returns for the Money Market Funds Average are derived from data provided by Lipper Inc. Keep in mind that the Fund’s past performance does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.

Annual Total Returns—Investor Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2010, was 0.02%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 1.59% (quarter ended December 31, 2000), and the lowest return for a quarter was 0.01% (quarter ended December 31, 2009).


Average Annual Total Returns for Periods Ended December 31, 2009
	1 Year	5 Years	10 Years
Vanguard Federal Money Market Fund Investor Shares	0.40%	3.14%	2.96%
Comparative Benchmarks
(Index reflects no deduction for fees or expenses)
Citigroup 3-Month U.S. Treasury Bill Index	0.16%	2.88%	2.84%
U.S. Government Money Market Funds Average	0.08	2.57	2.41

Investment Advisor
The Vanguard Group, Inc.

Portfolio Manager

John C. Lanius, Portfolio Manager of Vanguard. He has managed the Fund since 2007.

Purchase and Sale of Fund Shares
You may purchase or redeem shares online through our website at Vanguard.com, by mail (The Vanguard Group, P.O. Box 1110, Valley Forge, PA 19482-1110), or by telephone (800-662-2739). The following table provides the Fund’s minimum initial and subsequent investment requirements.


Account Minimums	Investor Shares
To open and maintain an account	$3,000
To add to an existing account	$100 (other than by Automatic Investment Plan,
	which has no established minimum)

Tax Information
The Fund’s distributions may be taxable as ordinary income or capital gain. Distributions are taxable to you for federal income tax purposes, whether or not you reinvest these amounts in additional Fund shares. Dividend distributions that you receive may also be subject to state and local income taxes.

Payments to Financial Intermediaries
The Fund and its investment advisor do not pay financial intermediaries for sales of Fund shares.

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