Mutual Fund Summary Prospectus (497k)

Vanguard Extended Market Index Fund

Summary Prospectus

April 12, 2013

Signal ^® Shares

Vanguard Extended Market Index Fund Signal Shares (VEMSX)

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

April 12, 2013, 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 (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 benchmark index that measures the investment return of small- and mid-capitalization stocks.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Signal Shares of the Fund. “Acquired Fund Fees and Expenses” are expenses incurred indirectly by the Fund through its ownership of shares in other investment companies, such as business development companies. Business development company expenses are similar to the expenses paid by any operating company held by the Fund. They are not direct costs paid by Fund shareholders and are not used to calculate the Fund’s net asset value. They have no impact on the costs associated with fund operations.


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	0.07%
12b-1 Distribution Fee	None
Other Expenses	0.03%
Acquired Fund Fees and Expenses	0.04%
Total Annual Fund Operating Expenses ¹	0.14%

1 Acquired Fund Fees and Expenses are not included in the Fund’s financial statements, which provide a clearer picture of a fund’s actual operating costs.

Example

The following example is intended to help you compare the cost of investing in the Fund’s Signal 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 total annual fund 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
$14	$45	$79	$179

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 more 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 12%.

Primary Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the Standard & Poor‘s Completion Index, a broadly diversified index of stocks of small and mid-size U.S. companies. The S&P Completion Index contains all of the U.S. common stocks regularly traded on the New York Stock Exchange and the Nasdaq over-the-counter market, except those stocks included in the S&P 500 Index. The Fund invests all, or substantially all, of its assets in stocks of its target index, with nearly 80% of its assets invested in approximately 1,200 of the stocks in its target index (covering nearly 85% of the Index’s total market capitalization), and the rest of its assets in a representative sample of the remaining stocks. The Fund holds a broadly diversified collection of securities that, in the aggregate, approximates the full Index in terms of key characteristics. These key characteristics include industry weightings and market capitalization, as well as certain financial measures, such as price/earnings ratio and dividend yield.

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 stock market. The Fund is subject to the following risks, which could affect the Fund’s performance:

• Stock market risk , which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. The Fund’s target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

• Investment style risk , which is the chance that returns from small- and mid-capitalization stocks will trail returns from the overall stock market. Historically, small-and mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently.

• 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 Signal Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Signal Shares compare with those of the Fund’s target index, which has 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.

Annual Total Returns — Vanguard Extended Market Index Fund Signal Shares

During the periods shown in the bar chart, the highest return for a calendar quarter was 21.73% (quarter ended June 30, 2009), and the lowest return for a quarter was –26.55% (quarter ended December 31, 2008).


Average Annual Total Returns for Periods Ended December 31, 2012
			Since
			Inception
			(Sep. 1,
	1 Year	5 Years	2006)
Vanguard Extended Market Index Fund Signal Shares
Return Before Taxes	18.48%	4.24%	5.53%
Return After Taxes on Distributions	18.12	3.97	5.22
Return After Taxes on Distributions and Sale of Fund Shares	12.32	3.54	4.67
Standard & Poor's Completion Index
(reflects no deduction for fees, expenses, or taxes)	18.45%	4.09%	5.41%

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 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 Manager

Donald M. Butler, CFA, Principal of Vanguard. He has managed the Fund since 1997.

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). Signal Shares generally are available to certain institutional and financial intermediary clients with no minimum initial or subsequent investment requirements.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gain.

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 Extended Market Index Fund Signal Shares—Fund Number 1342

CFA ^® is a trademark owned by CFA Institute.

S&P ^® and S&P 500 ^® are registered trademark of Standard & Poor’s Financial Services LLC (“S&P”). The trademarks have been licensed to S&P Dow Jones Indices LLC and its affiliates and have been sublicensed for use for certain purposes by Vanguard. The Standard & Poor’s Completion Index is a product of S&P Dow Jones Indices LLC and has been licensed for use by Vanguard. Vanguard Extended Market Index Fund is not sponsored, endorsed, sold or promoted by S&P Dow Jones Indices LLC, Dow Jones, S&P, or any of their respective affiliates (collectively, “S&P Dow Jones Indices”). S&P Dow Jones Indices make no representation or warranty, express or implied, to the owners of the Vanguard Extended Market Index Fund or any member of the public regarding the advisability of investing in securities generally or in Vanguard Extended Market Index Fund particularly or the ability of the Standard & Poor’s Completion Index to track general market performance. S&P Dow Jones Indices’ only relationship to Vanguard with respect to the Standard & Poor’s Completion Index is the licensing of the Index and certain trademarks, service marks and/or trade names of S&P Dow Jones Indices and/or its third party licensors. The Standard & Poor’s Completion Index is determined, composed and calculated by S&P Dow Jones Indices without regard to Vanguard or the Vanguard Extended Market Index Fund. S&P Dow Jones Indices have no obligation to take the needs of Vanguard or the owners of Vanguard Extended Market Index Fund into consideration in determining, composing or calculating the Standard & Poor’s Completion Index. S&P Dow Jones Indices are not responsible for and have not participated in the determination of the prices, and amount of Vanguard Extended Market Index Fund or the timing of the issuance or sale of Vanguard Extended Market Index Fund or in the determination or calculation of the equation by which Vanguard Extended Market Index Fund is to be converted into cash. S&P Dow Jones Indices has no obligation or liability in connection with the administration, marketing or trading of Vanguard Extended Market Index Fund. There is no assurance that investment products based on the Standard & Poor’s Completion Index will accurately track index performance or provide positive investment returns. S&P Dow Jones Indices LLC is not an investment advisor. Inclusion of a security within an index is not a recommendation by S&P Dow Jones Indices to buy, sell, or hold such security, nor is it considered to be investment advice.

S&P DOW JONES INDICES DOES NOT GUARANTEE THE ADEQUACY, ACCURACY, TIMELINESS AND/OR THE COMPLETENESS OF THE STANDARD & POOR’S COMPLETION INDEX OR ANY DATA RELATED THERETO OR ANY COMMUNICATION, INCLUDING BUT NOT LIMITED TO, ORAL OR WRITTEN COMMUNICATION (INCLUDING ELECTRONIC COMMUNICATIONS) WITH RESPECT THERETO. S&P DOW JONES INDICES SHALL NOT BE SUBJECT TO ANY LIABILITY FOR ANY ERRORS, OMISSIONS, OR DELAYS THEREIN. S&P DOW JONES INDICES MAKES NO EXPRESS OR IMPLIED WARRANTIES, AND EXPRESSLY DISCLAIMS ALL WARRANTIES OR CONDITIONS OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE AND ANY OTHER EXPRESS OR IMPLIED WARRANTY OR CONDITION WITH RESPECT TO THE STANDARD & POOR’S COMPLETION INDEX OR DATA INCLUDED THEREIN. WITHOUT LIMITING ANY OF THE FOREGOING, IN NO EVENT WHATSOEVER SHALL S&P DOW JONES INDICES BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO, LOSS OF PROFITS, TRADING LOSSES, LOST TIME OR GOODWILL, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES, WHETHER IN CONTRACT, TORT, STRICT LIABILITY, OR OTHERWISE.

SP 1342 042013