Vanguard Long-Term Bond Index Fund

Summary Prospectus 

April 26, 2011

Institutional Shares

Vanguard Long-Term Bond Index Fund Institutional Shares (VBLLX)

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

April 26, 2011, 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 (if you are an individual investor) or 888-809-8102

(if you are a client of Vanguard‘s Institutional Division), or by sending an e-mail

request to online@vanguard.com.

The Securities and Exchange Commission (SEC) has not approved or disapproved these securities or

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

Investment Objective
The Fund seeks to track the performance of a market-weighted bond index with a
long-term dollar-weighted average maturity.

Fees and Expenses
The following table describes the fees and expenses you may pay if you buy and hold
Institutional Shares of the Fund.

Shareholder Fees
(Fees paid directly from your investment)
Sales Charge (Load) Imposed on Purchases	None
Purchase Fee	None
Sales Charge (Load) Imposed on Reinvested Dividends	None
Redemption Fee	None

Annual Fund Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment)
Management Expenses	0.04%
12b-1 Distribution Fee	None
Other Expenses	0.03%
Total Annual Fund Operating Expenses	0.07%

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Example

The following example is intended to help you compare the cost of investing in the
Fund’s Institutional Shares 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 Shares provide 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
$7	$23	$40	$90

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells
securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate
higher transaction costs and may result in higher taxes when Fund shares are held in
a taxable account. These costs, which are not reflected in annual fund operating
expenses or in the previous expense example, reduce the Fund’s performance. During
the most recent fiscal year, the Fund’s portfolio turnover rate was 54%.

Primary Investment Strategies
The Fund employs a “passive management”—or indexing—investment approach
designed to track the performance of the Barclays Capital U.S. Long Government/Credit
Float Adjusted Index. This Index includes all medium and larger issues of U.S.
government, investment-grade corporate, and investment-grade international dollar-
denominated bonds that have maturities of greater than 10 years and are publicly issued.

The Fund invests by sampling the Index, meaning that it holds a range of securities that,
in the aggregate, approximates the full Index in terms of key risk factors and other
characteristics. All of the Fund’s investments will be selected through the sampling
process, and at least 80% of the Fund’s assets will be invested in bonds held in the
Index. The Fund maintains a dollar-weighted average maturity consistent with that of
the Index, which generally ranges between 15 and 30 years.

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Primary Risks
An investment in the Fund could lose money over short or even long periods. You should
expect the Fund’s share price and total return to fluctuate within a wide range, like the
fluctuations of the overall bond market. The Fund’s performance could be hurt by:

• Interest rate risk, which is the chance that bond prices overall will decline because
of rising interest rates. Interest rate risk should be high for the Fund because it invests
mainly in long-term bonds, whose prices are much more sensitive to interest rate
changes than are the prices of short-term bonds.

• Income risk, which is the chance that the Fund’s income will decline because of
falling interest rates. Income risk is generally low for long-term bond funds.

• Credit risk, which is the chance that a bond issuer 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 bond to decline. Credit risk should be
low for the Fund because it purchases only bonds that are of investment-grade quality.

• Index sampling risk, which is the chance that the securities selected for the Fund, in
the aggregate, will not provide investment performance matching that of the Fund’s
target index. Index sampling risk for the Fund should be low.

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.

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‘s
Institutional Shares has varied from one calendar year to another over the periods
shown. The table shows how the average annual total returns of the Institutional
Shares compare with those of the Fund‘s target index and other comparative indexes,
which have investment characteristics similar to those of the Fund. Keep in mind that
the Fund’s past performance (before and after taxes) 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.

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Annual Total Returns — Vanguard Long-Term Bond Index Fund Institutional Shares

During the periods shown in the bar chart, the highest return for a calendar quarter
was 13.07% (quarter ended December 31, 2008), and the lowest return for a quarter
was –6.13% (quarter ended March 31, 2009).

Average Annual Total Returns for Periods Ended December 31, 2010
		Since
		Inception
		(Feb. 2,
	1 Year	2006)
Vanguard Long-Term Bond Index Fund Institutional Shares
Return Before Taxes	10.44%	6.41%
Return After Taxes on Distributions	8.34	4.39
Return After Taxes on Distributions and Sale of Fund Shares	6.91	4.29
Comparative Indexes
(reflect no deduction for fees, expenses, or taxes)
Spliced Barclays Capital U.S. Long Gov/Credit Float Adjusted Index	10.16%	6.24%
Barclays Capital U.S. Long Gov/Credit Float Adjusted Index	10.16	—
Barclays Capital U.S. Long Gov/Credit Bond Index	10.16	6.23

Actual after-tax returns depend on your tax situation and may differ from those shown in
the preceding table. When after-tax returns are calculated, it is assumed that the
shareholder was in the highest individual federal marginal income tax bracket at the time
of each distribution of income or capital gains or upon redemption. State and local
income taxes are not reflected in the calculations. Please note that after-tax returns are
not relevant for a shareholder who holds fund shares in a tax-deferred account, such as
an individual retirement account or a 401(k) plan. Also, figures captioned Return After
Taxes on Distributions and Sale of Fund Shares will be higher than other figures for the

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same period if a capital loss occurs upon redemption and results in an assumed tax
deduction for the shareholder.

Investment Advisor
The Vanguard Group, Inc.

Portfolio Managers

Gregory Davis, CFA, Principal of Vanguard and head of Vanguard’s Bond Index Group.
He has co-managed the Fund since 2008.

Gerald Hwang, CFA, Portfolio Manager. He has co-managed the Fund since 2010.

Purchase and Sale of Fund Shares
You may purchase or redeem shares online through our website (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	Institutional Shares
To open and maintain an account	$25 million
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. A sale or exchange of Fund shares is a taxable
event, which means that you may have a capital gain to report as income, or a capital
loss to report as a deduction, when you complete your federal income tax return.
Dividend and capital gains distributions that you receive, as well as your gains or losses
from any sale or exchange of Fund shares, 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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Vanguard Long-Term Bond Index Fund Institutional Shares—Fund Number 545

CFA^® is a trademark owned by CFA Institute.

© 2011 The Vanguard Group, Inc. All rights reserved.

Vanguard Marketing Corporation, Distributor.

SPI 545 042011