Admiral Shares for Participants | Vanguard Mid-Cap Growth Index Fund

Vanguard Mid-Cap Growth Index Fund

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization growth stocks.

Fees and Expenses

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

Shareholder Fees

(Fees paid directly from your investment)

Shareholder Fees	Admiral Shares for Participants Vanguard Mid-Cap Growth Index Fund Admiral Shares
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)

Annual Fund Operating Expenses	Admiral Shares for Participants Vanguard Mid-Cap Growth Index Fund Admiral Shares
Management Fees	0.06%
12b-1 Distribution Fee	none
Other Expenses	0.02%
Total Annual Fund Operating Expenses	0.08%

Example

The following example is intended to help you compare the cost of investing in the Fund’s Admiral 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:

Expense Example	1 Year	3 Years	5 Years	10 Years
Admiral Shares for Participants | Vanguard Mid-Cap Growth Index Fund | Admiral Shares | USD ($)	8	26	45	103

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 23% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mid Cap Growth Index, a broadly diversified index of growth stocks of mid-size U.S. companies. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

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 mid-capitalization growth stocks will trail returns from the overall stock market. Historically, 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. Mid-size companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

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 Admiral Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Admiral 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 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 Mid-Cap Growth Index Fund Admiral Shares

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.68% (quarter ended March 31, 2012), and the lowest return for a quarter was –8.23% (quarter ended September 30, 2015).

Average Annual Total Returns for Periods Ended December 31, 2015

Average Annual Total Returns - Admiral Shares for Participants - Vanguard Mid-Cap Growth Index Fund		1 Year	Since Inception	Inception Date
Admiral Shares		(0.98%)	14.42%	Sep. 27, 2011
MSCI US Mid Cap Growth Index	[1]	(0.06%)	16.07%	Sep. 27, 2011
Spliced Mid Cap Growth Index	[1]	(0.93%)	14.46%	Sep. 27, 2011
CRSP US Mid Cap Growth Index	[1]	(0.93%)		Sep. 27, 2011

[1] Comparative Indexes (reflect no deduction for fees or expenses)