Label

Element

Value

Risk/Return:

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Registrant Name

dei_EntityRegistrantName

VANGUARD INDEX FUNDS

Prospectus Date

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Apr. 26, 2019

Supplement to Prospectus [Text Block]

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[SHIP LOGO VANGUARD (R)]

Vanguard Growth Index Fund

Supplement Dated July 29, 2019, to the Prospectus and Summary Prospectus Dated April 26, 2019

The Board of Trustees of Vanguard Growth Index Fund has approved a change to the Fund’s diversification policy under the Investment Company Act of 1940. Under the revised policy, the Fund will continue to track its target index even if the Fund becomes nondiversified as a result of a change in relative market capitalization or index weighting of one or more constituents of the index.

Shareholder approval will not be sought if the Fund crosses from diversified to nondiversified status under such circumstances.

Prospectus and Summary Prospectus Text Changes

The following is added under the heading “Principal Investment Strategies”:

The Fund may become nondiversified, as defined under the Investment Company Act of 1940, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index.

The following is added under the heading “Principal Risks”:

• Sector risk, which is the chance that significant problems will affect a particular sector, or that returns from that sector will trail returns from the overall stock market. Daily fluctuations in specific market sectors are often more extreme or volatile than fluctuations in the overall market. Because a significant portion of the Fund’s assets are in the information technology sector, the Fund’s performance is impacted by the general condition of that sector. Companies in the information technology sector could be affected by, among other things, overall economic conditions, short product cycles, and rapid obsolescence of products, competition, and government regulation. Sector risk is expected to be high for the Fund.

© 2019 The Vanguard Group, Inc. All rights reserved.

Vanguard Marketing Corporation, Distributor. PS 09B 072019

Vanguard Growth Index Fund

Risk/Return:

rr_RiskReturnAbstract

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

[SHIP LOGO VANGUARD (R)]

Vanguard Growth Index Fund

Supplement Dated July 29, 2019, to the Prospectus and Summary Prospectus Dated April 26, 2019

The Board of Trustees of Vanguard Growth Index Fund has approved a change to the Fund’s diversification policy under the Investment Company Act of 1940. Under the revised policy, the Fund will continue to track its target index even if the Fund becomes nondiversified as a result of a change in relative market capitalization or index weighting of one or more constituents of the index.

Shareholder approval will not be sought if the Fund crosses from diversified to nondiversified status under such circumstances.

Prospectus and Summary Prospectus Text Changes

The following is added under the heading “Principal Investment Strategies”:

The Fund may become nondiversified, as defined under the Investment Company Act of 1940, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index.

The following is added under the heading “Principal Risks”:

• Sector risk, which is the chance that significant problems will affect a particular sector, or that returns from that sector will trail returns from the overall stock market. Daily fluctuations in specific market sectors are often more extreme or volatile than fluctuations in the overall market. Because a significant portion of the Fund’s assets are in the information technology sector, the Fund’s performance is impacted by the general condition of that sector. Companies in the information technology sector could be affected by, among other things, overall economic conditions, short product cycles, and rapid obsolescence of products, competition, and government regulation. Sector risk is expected to be high for the Fund.

© 2019 The Vanguard Group, Inc. All rights reserved.

Vanguard Marketing Corporation, Distributor. PS 09B 072019