prosummary.htm

Summary Prospectus November 1, 2010 American Century Investments® Small Company Fund
Investor Class: ASQIX Institutional Class: ASCQX	A Class: ASQAX C Class: ASQCX	R Class: ASCRX

	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 the web addresses listed below. You can also get this information at no cost by calling or sending an email request. The fund’s prospectus and other information are also available from financial intermediaries (such as banks and broker-dealers) through which shares of the fund may be purchased or sold.

	Retail Investors americancentury.com/funds/fund_reports.jsp 1-800-345-2021 or 816-531-5575 prospectus@americancentury.com	Financial Professionals americancentury.com/ipro/funds/fund_reports_mf.jsp 1-800-345-6488 advisor_prospectus@americancentury.com

	This summary prospectus incorporates by reference the fund’s prospectus and statement of additional information (SAI), each dated November 1, 2010 (as supplemented at the time you receive this summary prospectus), as well as the Report of Independent Registered Public Accounting Firm and the financial statements included in the fund’s annual report to shareholders, dated June 30, 2010. The fund's SAI and annual report may be obtained, free of charge, in the same manner as the prospectus.

Investment Objective

The fund seeks long-term capital growth by investing primarily in stocks of small companies.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in American Century Investments funds. More information about these and other discounts, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus and Sales Charges on page 67 of the statement of additional information.


Shareholder Fees (fees paid directly from your investment)
	Investor	Institutional	A	C	R
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	None	None	5.75%	None	None
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds)	None	None	None	1.00%	None
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000)	$25	None	None	None	None
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Investor	Institutional	A	C	R
Management Fee	0.89%	0.69%	0.89%	0.89%	0.89%
Distribution and Service (12b-1) Fees	None	None	0.25%	1.00%	0.50%
Other Expenses	0.01%	0.01%	0.01%	0.01%	0.01%
Total Annual Fund Operating Expenses	0.90%	0.70%	1.15%	1.90%	1.40%

Example

The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds. The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. 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
Investor Class	$92	$287	$499	$1,108
Institutional Class	$72	$224	$390	$871
A Class	$686	$920	$1,172	$1,892
C Class	$193	$598	$1,027	$2,219
R Class	$143	$444	$767	$1,679

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 higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 44% of the average value of its portfolio.

Principal Investments, Principal Risks and Performance

Under normal market conditions, the fund will invest at least 80% of its assets in stocks of smaller-capitalization U.S. companies. The portfolio managers consider small companies to be those that, at the time of investment, have a market capitalization not greater than that of the largest company in the S&P SmallCap 600 Index. The portfolio managers use quantitative management techniques in a two-step process. First, the managers rank stocks, primarily smaller U.S. companies, from most attractive to least attractive based on each stock’s value as well as its growth potential. Second, the portfolio managers use a quantitative model to build a portfolio of stocks from the ranking described above that they believe will provide the optimal balance between risk and expected return.

The portfolio managers generally sell a stock when they believe it has become less attractive relative to other opportunities, its risk characteristics outweigh its return opportunity or specific events alter its prospects.

The fund’s principal risks include:

•	Small Cap Stocks – The smaller companies in which the fund invests may be more volatile and subject to greater risk than larger companies. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs.

•	Style Risk – If at any time the market is not favoring the fund’s quantitative investment style, the fund’s gains may not be as big as, or its losses may be bigger than, other equity funds using different investment styles.

•	Benchmark Correlation – The fund’s performance will be tied to the performance of its benchmark, the S&P SmallCap 600 Index. If the fund’s benchmark goes down, it is likely that the fund’s performance will go down.

•	Market Risk – The value of the fund’s shares will go up and down based on the performance of the companies whose securities it owns and other factors generally affecting the securities market.

•	Price Volatility – The value of the fund’s shares may fluctuate significantly in the short term.

•	Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Annual Total Returns

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, please visit americancentury.com.

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Highest Performance Quarter

(2Q 2003): 22.31%

Lowest Performance Quarter

(4Q 2008): -26.86%

As of September 30, 2010, the most

recent calendar quarter end, the fund's

Investor Class year-to-date return was 10.17%.

For the calendar year ended December 31, 2009	1 year	5 years	10 years	Since Inception	Inception Date
Investor Class Return Before Taxes	20.46%	-4.39%	5.51%	5.71%	07/31/1998
Return After Taxes on Distributions	20.40%	-5.38%	4.59%	4.89%	07/31/1998
Return After Taxes on Distributions and Sale of Fund Shares	13.37%	-3.69%	4.64%	4.85%	07/31/1998
Institutional Class Return Before Taxes	20.74%	-4.18%	5.72%	7.05%	10/01/1999
A Class(1) Return Before Taxes	13.22%	-5.77%	—	3.42%	09/07/2000
C Class(2) Return Before Taxes	19.26%	-5.34%	4.46%	4.66%	03/01/2010
R Class Return Before Taxes	19.84%	-4.85%	—	2.66%	08/29/2003
S&P SmallCap 600 Index (reflects no deduction for fees, expenses or taxes)	25.57%	1.36%	6.35%	6.70%	07/31/1998

1	Prior to March 1, 2010, the A Class was referred to as the Advisor Class and did not have a front-end sales charge. Performance prior to that date has been restated to reflect this charge.

2	Historical performance for C Class prior to its inception is based on the performance of Investor Class shares. C Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.

The after-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

Portfolio Management

Investment Advisor

American Century Investment Management, Inc.

Portfolio Managers

Brian L. Garbe, Vice President and Portfolio Manager, has been a member of the team that manages the fund since 2010.

Tal Sansani, CFA, Portfolio Manager and Quantitative Analyst, has been a member of the team that manages the fund since 2005.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the fund on any business day through our Web site at americancentury.com, by mail (American Century Investments, P.O. Box 419200, Kansas City, MO 64141-6200), or by telephone at 1-800-345-2021 (Investor Services Representative) or 1-800-345-3533 (Business, Not-For-Profit and Employer-Sponsored Retirement Plans). Shares may be purchased by electronic bank transfer, by check or by wire. You may receive redemption proceeds by electronic bank transfer or by check.

Unless otherwise specified below, the minimum initial investment amount to open an account is $2,500. Financial intermediaries may open an account with $250, but may require their clients to meet different investment minimums. Broker-dealer sponsored wrap program accounts, fee based accounts, and employer-sponsored retirement plan accounts (in classes other than Institutional Class) do not have a minimum purchase amount. The minimum initial investment amount for Coverdell Education Savings Accounts is $2,000 unless the account is opened through a financial intermediary.

The minimum initial investment amount for Institutional Class is generally $5 million ($3 million for endowments and foundations).

There is a $50 minimum for subsequent purchases, except that there is no subsequent purchase minimum for financial intermediaries or employer-sponsored retirement plans. For purposes of fund minimums, employer-sponsored retirement plans do not include SEP IRAs, SIMPLE IRAs or SARSEPs.

Tax Information

Fund distributions are generally taxable as ordinary income or capital gains, unless you are investing through a tax-deferred account such as a 401(k) or individual retirement account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the fund through a broker-dealer or other financial intermediary (such as a bank, insurance company, plan sponsor or financial professional), the fund and its related companies may pay the intermediary for the sale of fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the fund over another investment. Ask your salesperson or visit your financial intermediary’s Web site for more information.

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