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Vanguard Extended Market Index Fund

Summary Prospectus

April 27, 2016

Investor Shares for Participants

Vanguard Extended Market Index Fund Investor Shares (VEXMX)

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

April 27, 2016, as may be amended or supplemented, 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 obtain this information at no

cost by calling 800-523-1188 or by sending an email 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 Investor 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 Fees	0.19%
12b-1 Distribution Fee	None
Other Expenses	0.03%
Total Annual Fund Operating Expenses	0.22%

Example

The following example is intended to help you compare the cost of investing in the Fund’s Investor Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $10,000 in the Fund’s shares. This example assumes that the Shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses 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

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 6% of the average value of its portfolio.

Principal 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 by sampling the Index, meaning that it holds a broadly diversified collection of securities that, in the aggregate, approximates the full Index in terms of key characteristics. These characteristics include industry weightings and market capitalization, as well as certain financial measures, such as price/earnings ratio and dividend yield.

Principal 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. 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 tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

• 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. Small and mid-size companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

• 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 Investor Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Investor Shares compare with those of the Fund‘s target index and a comparative index, which have investment characteristics similar to those of the Fund. 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 — Vanguard Extended Market Index Fund Investor Shares

During the periods shown in the bar chart, the highest return for a calendar quarter was 21.69% (quarter ended June 30, 2009), and the lowest return for a quarter was –26.60% (quarter ended December 31, 2008).

Average Annual Total Returns for Periods Ended December 31, 2015


	1 Year	5 Years	10 Years
Vanguard Extended Market Index Fund Investor Shares	–3.39%	10.31%	7.64%
Comparative Indexes
(reflect no deduction for fees or expenses)
Standard & Poor's Completion Index	–3.35%	10.37%	7.68%
Spliced Dow Jones U.S. Completion Total Stock Market Index	–3.42	10.24	7.90

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has managed the Fund since 1997 (co-managed since 2016).

Scott E. Geiger, Portfolio Manager at Vanguard. He has co-managed the Fund since 2016.

Tax Information

The Fund’s distributions will be reinvested in additional Fund shares and accumulate on a tax-deferred basis if you are investing through an employer-sponsored retirement or savings plan. You will not owe taxes on these distributions until you begin withdrawals from the plan. You should consult your plan administrator, your plan’s Summary Plan Description, or your tax advisor about the tax consequences of plan withdrawals.

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 Investor Shares—Fund Number 98

CFA^®is a registered trademark owned by CFA Institute.

The Standard & Poor’s Completion Index (the “Index”) is a product of S&P Dow Jones Indices LLC (“SPDJI”), and has been licensed for use by Vanguard. Standard & Poor’s^®and S&P^®are registered trademarks of Standard & Poor’s Financial Services LLC (“S&P”); Dow Jones^®is a registered trademark of Dow Jones Trademark Holdings LLC (“Dow Jones”); S&P^®and S&P 500^®are trademarks of S&P; and these trademarks have been licensed for use by SPDJI and sublicensed for certain purposes by Vanguard. Vanguard Extended Market Index Fund is not sponsored, endorsed, sold or promoted by SPDJI, Dow Jones, S&P, 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 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, surrendered or redeemed, as the case may be. S&P Dow Jones Indices have 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 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 DAMAGES OR LIABILITY FOR ANY ERRORS, OMISSIONS, OR DELAYS THEREIN. S&P DOW JONES INDICES MAKE NO EXPRESS OR IMPLIED WARRANTIES, AND EXPRESSLY DISCLAIMS ALL WARRANTIES, OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE OR AS TO RESULTS TO BE OBTAINED BY VANGUARD, OWNERS OF THE VANGUARD EXTENDED MARKET INDEX FUND, OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE INDEX OR WITH RESPECT TO ANY DATA RELATED THERETO. 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. THERE ARE NO THIRD PARTY BENEFICIARIES OF ANY AGREEMENTS OR ARRANGEMENTS BETWEEN S&P DOW JONES INDICES AND VANGUARD, OTHER THAN THE LICENSORS OF S&P DOW JONES INDICES.

SPI 098 042016