485BPOS

As filed with the Securities and Exchange Commission on November 21, 2012

File Nos. 2-10768

811-00204

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	¨
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 151	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 155 x

ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC.

(Exact Name of Registrant as Specified in Charter)

1345 Avenue of the Americas, New York, New York 10105

(Address of Principal Executive Office) (Zip Code)

Registrant’s Telephone Number, including Area Code:

(800) 221-5672

EMILIE D. WRAPP

AllianceBernstein L.P.

1345 Avenue of the Americas

New York, New York 10105

(Name and address of agent for service)

Copies of communications to:

Kathleen K. Clarke

Seward & Kissel LLP

901 K Street, N.W.

Suite 800

Washington, DC 20001

It is proposed that this filing will become effective (check appropriate box)

¨ immediately upon filing pursuant to paragraph (b)

x on November 21, 2012 pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)(1)

¨ on (date) pursuant to paragraph (a)(1)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

¨ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Amendment to its Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of New York and the State of New York, on the 21st day of November, 2012.

ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC.
By:	Robert M. Keith*
	Robert M. Keith President

Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated:

	Signature	Title	Date
(1)	Principal Executive Officer:
	Robert M. Keith* Robert M. Keith	President and Chief Executive Officer	November 21, 2012
(2)	Principal Financial and Accounting Officer:
	/s/    Joseph J. Mantineo Joseph J. Mantineo	Treasurer and Chief Financial Officer	November 21, 2012
(3)	All of the Directors:
	John H. Dobkin* Michael J. Downey* William H. Foulk, Jr.* D. James Guzy* Nancy P. Jacklin* Robert M. Keith* Garry L. Moody* Marshall C. Turner, Jr.* Earl D. Weiner*
*By:	/s/    Stephen J. Laffey Stephen J. Laffey (Attorney-in-fact)		November 21, 2012

Index to Exhibits

Exhibit No.	Description of Exhibits
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CALC	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC.
Prospectus Date	rr_ProspectusDate	Nov. 01, 2012
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC.
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	AllianceBernstein Discovery Growth Fund (formerly AllianceBernstein Small/Mid Cap Growth Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment objective is long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds. More information about these and other discounts is available from your financial intermediary and in Investing in the Funds——Sales Charge Reduction Programs for Class A Shares on page 53 of this Prospectus and in Purchase of Shares——Sales Charge Reduction Programs for Class A Shares on page 113 of the Funds’ SAI.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys or 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 transaction costs, which are not reflected in the Annual Fund Operating Expenses or in the Examples, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 86% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	86.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	100,000
Expense Example [Heading]	rr_ExpenseExampleHeading	Examples
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Examples are intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Examples assume 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. The Examples also assume that your investment has a 5% return each year and that the Fund’s operating expenses stay the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	For the share classes listed below, you would pay the following expenses if you did not redeem your shares at the end of the period.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests primarily in a diversified portfolio of equity securities with relatively smaller capitalizations as compared to the overall U.S. market. Under normal circumstances, the Fund invests at least 80% of its net assets in the equity securities of small- and mid-capitalization companies. For these purposes, “small- and mid-capitalization companies” are generally those companies that, at the time of investment, fall within the lowest 25% of the total U.S. equity market capitalization (excluding, for purposes of this calculation, companies with market capitalizations of less than $10 million). As of June 30, 2012, there were approximately 4,350 companies within the lowest 25% of the total U.S. equity market capitalization (excluding companies with market capitalizations of less than $10 million) with market capitalizations ranging from $10 million to $12.7 billion. Because the Fund’s definition of small- and mid-capitalization companies is dynamic, the limits on market capitalization will change with the markets. In the future, the Fund may define small- and mid-capitalization companies using a different classification system. The Fund may invest in any company and industry and in any type of equity security with potential for capital appreciation. It invests in well-known and established companies and in new and less-seasoned companies. The Fund’s investment policies emphasize investments in companies that are demonstrating improving financial results and a favorable earnings outlook. The Fund may invest in foreign securities. When selecting securities, the Adviser typically looks for companies that have strong, experienced management teams, strong market positions, and the potential to support greater than expected earnings growth rates. In making specific investment decisions for the Fund, the Adviser combines fundamental and quantitative analysis in its stock selection process. The Fund may periodically invest in the securities of companies that are expected to appreciate due to a development particularly or uniquely applicable to that company regardless of general business conditions or movements of the market as a whole. Normally, the Fund invests in approximately 60-120 companies broadly diversified by sector. The Fund invests principally in equity securities but may also invest in other types of securities, such as preferred stocks. The Fund may, at times, invest in shares of ETFs in lieu of making direct investments in securities. ETFs may provide more efficient and economical exposure to the types of companies and geographic locations in which the Fund seeks to invest than direct investments. The Fund may also invest up to 20% of its total assets in rights and warrants. The Fund may enter into derivatives transactions, such as options, futures contracts, forwards and swaps to manage risk and to seek to generate additional returns. The Fund may use options strategies involving the purchase and/or writing of various combinations of call and/or put options, including on individual securities and stock indexes, futures contracts (including futures contracts on individual securities and stock indexes) or shares of ETFs. These transactions may be used, for example, in an effort to earn extra income, to adjust exposure to individual securities or markets, or to protect all or a portion of the Fund’s portfolio from a decline in value, sometimes within certain ranges.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Market Risk: The value of the Fund’s assets will fluctuate as the stock or bond market fluctuates. The value of its investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. It includes the risk that a particular style of investing, such as growth, may underperform the market generally. Capitalization Risk: Investments in small- and mid-capitalization companies may be more volatile than investments in large-capitalization companies. Investments in small-capitalization companies may have additional risks because these companies have limited product lines, markets or financial resources. Foreign (Non-U.S.) Risk: Investments in securities of non-U.S. issuers may involve more risk than those of U.S. issuers. These securities may fluctuate more widely in price and may be less liquid due to adverse market, economic, political, regulatory or other factors. Derivatives Risk: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Fund, and may be subject to counterparty risk to a greater degree than more traditional investments. Management Risk: The Fund is subject to management risk because it is an actively managed investment fund. The Adviser will apply its investment techniques and risk analyses in making investment decisions for the Fund, but there is no guarantee that its techniques will produce the intended results. As with all investments, you may lose money by investing in the Fund.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, you may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	BAR CHART AND PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and performance information provide an indication of the historical risk of an investment in the Fund by showing: how the Fund’s performance changed from year to year over ten years; and how the Fund’s average annual returns for one, five and ten years compare to those of a broad-based securities market index. You may obtain updated performance information on the Fund’s website at www.AllianceBernstein.com (click on “Individuals – U.S.” then “Pricing & Performance”). The Fund’s past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future. IN NOVEMBER 2008, THE FUND IMPLEMENTED ITS CURRENT INVESTMENT POLICIES (PREVIOUSLY IT HAD INVESTED PRIMARILY IN “MID-CAPITALIZATION” COMPANIES) AND ALSO CHANGED ITS NAME AND PORTFOLIO MANAGEMENT TEAM AT THAT TIME. ACCORDINGLY, THE PERFORMANCE SHOWN BELOW FOR PERIODS PRIOR TO NOVEMBER 2008 MAY NOT BE REPRESENTATIVE OF THE FUND’s PERFORMANCE UNDER ITS CURRENT INVESTMENT POLICIES. EFFECTIVE NOVEMBER 1, 2012, THE FUND CHANGED ITS NAME TO ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	• how the Fund’s performance changed from year to year over ten years; and • how the Fund’s average annual returns for one, five and ten years compare to those of a broad-based securities market index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.AllianceBernstein.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	BAR CHART
Bar Chart Narrative [Text Block]	rr_BarChartNarrativeTextBlock	The annual returns in the bar chart are for the Fund’s Class A shares and do not reflect sales loads. If sales loads were reflected, returns would be less than those shown. Through September 30, 2012, the year-to-date unannualized return for Class A shares was 14.04%.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The annual returns in the bar chart are for the Fund’s Class A shares and do not reflect sales loads. If sales loads were reflected, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the period shown in the bar chart, the Fund’s: Best Quarter was up 24.27%, 2nd quarter, 2003; and Worst Quarter was down -30.35%, 4th quarter, 2008.
Performance Table Heading	rr_PerformanceTableHeading	Performance Table Average Annual Total Returns (For the periods ended December 31, 2011)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	Are an estimate, which is based on the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes;
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns:     – Are shown for Class A shares only and will vary for Class B, Class C and Advisor Class shares because these Classes have different expense ratios;
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | CLASS A
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.25%
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.23%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.13%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.10%
Total Other Expenses	rr_OtherExpensesOverAssets	0.23%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.19%
After 1 Year	rr_ExpenseExampleYear01	541
After 3 Years	rr_ExpenseExampleYear03	787
After 5 Years	rr_ExpenseExampleYear05	1,052
After 10 Years	rr_ExpenseExampleYear10	1,807
02	rr_AnnualReturn2002	(32.72%)
03	rr_AnnualReturn2003	65.96%
04	rr_AnnualReturn2004	19.23%
05	rr_AnnualReturn2005	6.71%
06	rr_AnnualReturn2006	1.36%
07	rr_AnnualReturn2007	11.88%
08	rr_AnnualReturn2008	(48.52%)
09	rr_AnnualReturn2009	46.96%
10	rr_AnnualReturn2010	39.08%
11	rr_AnnualReturn2011	3.64%
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	14.04%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	24.27%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(30.35%)
1 YEAR	rr_AverageAnnualReturnYear01	(0.79%)	[2]
5 YEARS	rr_AverageAnnualReturnYear05	3.16%	[2]
10 YEARS	rr_AverageAnnualReturnYear10	5.33%	[2]
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | CLASS B
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	(NOT CURRENTLY OFFERED TO NEW INVESTORS)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.00%	[3]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.24%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.09%
Total Other Expenses	rr_OtherExpensesOverAssets	0.33%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.06%
After 1 Year	rr_ExpenseExampleYear01	609
After 3 Years	rr_ExpenseExampleYear03	846
After 5 Years	rr_ExpenseExampleYear05	1,108
After 10 Years	rr_ExpenseExampleYear10	2,166
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	209
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	646
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,108
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	2,166
1 YEAR	rr_AverageAnnualReturnYear01	(1.17%)
5 YEARS	rr_AverageAnnualReturnYear05	3.19%
10 YEARS	rr_AverageAnnualReturnYear10	5.06%
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | CLASS C
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[4]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.15%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.09%
Total Other Expenses	rr_OtherExpensesOverAssets	0.24%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.97%
After 1 Year	rr_ExpenseExampleYear01	300
After 3 Years	rr_ExpenseExampleYear03	618
After 5 Years	rr_ExpenseExampleYear05	1,062
After 10 Years	rr_ExpenseExampleYear10	2,296
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	200
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	618
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,062
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	2,296
1 YEAR	rr_AverageAnnualReturnYear01	1.83%
5 YEARS	rr_AverageAnnualReturnYear05	3.23%
10 YEARS	rr_AverageAnnualReturnYear10	4.93%
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | ADVISOR CLASS
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.12%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.10%
Total Other Expenses	rr_OtherExpensesOverAssets	0.22%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.95%
After 1 Year	rr_ExpenseExampleYear01	97
After 3 Years	rr_ExpenseExampleYear03	303
After 5 Years	rr_ExpenseExampleYear05	525
After 10 Years	rr_ExpenseExampleYear10	1,166
1 YEAR	rr_AverageAnnualReturnYear01	3.83%
5 YEARS	rr_AverageAnnualReturnYear05	4.27%
10 YEARS	rr_AverageAnnualReturnYear10	6.03%
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | CLASS R
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.26%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.09%
Total Other Expenses	rr_OtherExpensesOverAssets	0.35%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.58%
After 1 Year	rr_ExpenseExampleYear01	161
After 3 Years	rr_ExpenseExampleYear03	499
After 5 Years	rr_ExpenseExampleYear05	860
After 10 Years	rr_ExpenseExampleYear10	1,878
1 YEAR	rr_AverageAnnualReturnYear01	3.20%	[5]
5 YEARS	rr_AverageAnnualReturnYear05	3.72%	[5]
10 YEARS	rr_AverageAnnualReturnYear10	5.51%	[5]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2005	[5]
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | CLASS K
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.19%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.09%
Total Other Expenses	rr_OtherExpensesOverAssets	0.28%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.26%
After 1 Year	rr_ExpenseExampleYear01	128
After 3 Years	rr_ExpenseExampleYear03	400
After 5 Years	rr_ExpenseExampleYear05	692
After 10 Years	rr_ExpenseExampleYear10	1,523
1 YEAR	rr_AverageAnnualReturnYear01	3.47%	[5]
5 YEARS	rr_AverageAnnualReturnYear05	4.03%	[5]
10 YEARS	rr_AverageAnnualReturnYear10	5.80%	[5]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2005	[5]
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | CLASS I
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.72%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.02%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.07%
Total Other Expenses	rr_OtherExpensesOverAssets	0.09%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.82%
After 1 Year	rr_ExpenseExampleYear01	84
After 3 Years	rr_ExpenseExampleYear03	262
After 5 Years	rr_ExpenseExampleYear05	455
After 10 Years	rr_ExpenseExampleYear10	1,014
1 YEAR	rr_AverageAnnualReturnYear01	4.03%	[5]
5 YEARS	rr_AverageAnnualReturnYear05	4.47%	[5]
10 YEARS	rr_AverageAnnualReturnYear10	6.17%	[5]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2005	[5]
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | Return After Taxes on Distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(0.79%)	[2]
5 YEARS	rr_AverageAnnualReturnYear05	2.74%	[2]
10 YEARS	rr_AverageAnnualReturnYear10	4.73%	[2]
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | Return After Taxes on Distributions and Sale of Fund Shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(0.51%)	[2]
5 YEARS	rr_AverageAnnualReturnYear05	2.67%	[2]
10 YEARS	rr_AverageAnnualReturnYear10	4.50%	[2]
ALLIANCEBERNSTEIN DISCOVERY GROWTH FUND, INC. | Russell 2500(R) Growth Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(1.57%)
5 YEARS	rr_AverageAnnualReturnYear05	2.89%
10 YEARS	rr_AverageAnnualReturnYear10	5.23%

[1] Purchases of Class A shares in amounts of $1,000,000 or more, or by certain group retirement plans, may be subject to a 1%, 1-year CDSC, which may be subject to waiver in certain circumstances.

[2] After-tax returns: -Are shown for Class A shares only and will vary for Class B, Class C and Advisor Class shares because these Classes have different expense ratios; -Are an estimate, which is based on the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes; actual after-tax returns depend on an individual investor's tax situation and are likely to differ from those shown; and -Are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[3] Class B shares automatically convert to Class A shares after eight years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the fourth year.

[4] For Class C shares the CDSC is 0% after the first year.

[5] Inception dates for Class R, Class K and Class I shares: 3/1/05. Performance information for periods prior to the inception of Class R, Class K and Class I shares is the performance of the Fund's Class A shares adjusted to reflect the higher expense ratio of the Class R shares and the lower expense ratios of Class K and Class I shares, respectively.