VB Vanguard Small Cap

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF
REGISTERED MANAGEMENT COMPANY

Investment Company Act file number: 811-02652

Name of Registrant: Vanguard Index Funds

Address of Registrant:
P.O. Box 2600
Valley Forge, PA 19482

Name and address of agent for service:
Heidi Stam, Esquire
P.O. Box 876
Valley Forge, PA 19482

Date of fiscal year end: December 31

Date of reporting period: March 31, 2013

Item 1: Schedule of Investments

* Non-income-producing security.
^ Part of security position is on loan to broker-dealers. The total value of securities on loan is $94,428,000.
1 The fund invests a portion of its cash reserves in equity markets through the use of index futures contracts. After giving effect to futures investments, the fund's effective common stock and temporary cash investment positions represent 100.0% and 0.2%, respectively, of net assets.
2 Affiliated money market fund available only to Vanguard funds and certain trusts and accounts managed by Vanguard. Rate shown is the 7-day yield.
3 Includes $98,464,000 of collateral received for securities on loan.
4 The issuer was placed under federal conservatorship in September 2008; since that time, its daily operations have been managed by the Federal Housing Finance Agency and it receives capital from the U.S. Treasury, as needed to maintain a positive net worth, in exchange for senior preferred stock.
5 Securities with a value of $31,310,000 have been segregated as initial margin for open futures contracts.
6 The issuer operates under a congressional charter; its securities are generally neither guaranteed by the U.S. Treasury nor backed by the full faith and credit of the U.S. government.
REIT—Real Estate Investment Trust.

500 Index Fund

A. Security Valuation: Securities are valued as of the close of trading on the New York Stock Exchange (generally 4 p.m., Eastern time) on the valuation date. Equity securities are valued at the latest quoted sales prices or official closing prices taken from the primary market in which each security trades; such securities not traded on the valuation date are valued at the mean of the latest quoted bid and asked prices. Securities for which market quotations are not readily available, or whose values have been materially affected by events occurring before the fund's pricing time but after the close of the securities’ primary markets, are valued by methods deemed by the board of trustees to represent fair value. Investments in Vanguard Market Liquidity Fund are valued at that fund's net asset value. Temporary cash investments acquired over 60 days to maturity are valued using the latest bid prices or using valuations based on a matrix system (which considers such factors as security prices, yields, maturities, and ratings), both as furnished by independent pricing services. Other temporary cash investments are valued at amortized cost, which approximates market value.

B. Various inputs may be used to determine the value of the fund's investments. These inputs are summarized in three broad levels for financial statement purposes. The inputs or methodologies used to value securities are not necessarily an indication of the risk associated with investing in those securities.

Level 1—Quoted prices in active markets for identical securities.
Level 2—Other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk, etc.).
Level 3—Significant unobservable inputs (including the fund's own assumptions used to determine the fair value of investments).

The following table summarizes the market value of the fund's investments as of March 31, 2013, based on the inputs used to value them:

C. Futures Contracts: The fund uses index futures contracts to a limited extent, with the objectives of maintaining full exposure to the stock market, enhancing returns, maintaining liquidity, and minimizing transaction costs. The fund may purchase futures contracts to immediately invest incoming cash in the market, or sell futures in response to cash outflows, thereby simulating a fully invested position in the underlying index while maintaining a cash balance for liquidity. The fund may seek to enhance returns by using futures contracts instead of the underlying securities when futures are believed to be priced more attractively than the underlying securities. The primary risks associated with the use of futures contracts are imperfect correlation between changes in market values of stocks held by the fund and the prices of futures contracts, and the possibility of an illiquid market.

Futures contracts are valued at their quoted daily settlement prices. The aggregate principal amounts of the contracts are not recorded in the Schedule of Investments. Fluctuations in the value of the contracts are recorded in the Schedule of Investments as an asset (liability).