485BPOS

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

File Nos. 2-29901

811-01716

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. 131	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 110 x

ALLIANCEBERNSTEIN CAP 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, NW

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 December 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.

This Post-Effective Amendment No. 131 relates solely to the Class A, Class C, Advisor Class, Class R, Class K and Class I shares, as applicable, of the AllianceBernstein Select US Long/Short Portfolio. No information in the Registrant’s Registration Statement relating to the Class A, Class B, Class C, Class R, Class K, Class I and Advisor Class shares, as applicable, of the AllianceBernstein Small Cap Growth Portfolio, the Class A, Class C, Class R, Class K, Class I and Advisor Class shares, as applicable, of the AllianceBernstein U.S. Strategic Research Portfolio, the Class A, Class C, Class R, Class K, Class I and Advisor Class shares, as applicable, of the AllianceBernstein Market Neutral Strategy - U.S., the Class A, Class C, Class R, Class K, Class I and Advisor Class shares, as applicable, of the AllianceBernstein Market Neutral Strategy - Global, the Class A, Class C, Advisor Class, Class R, Class K and Class I shares, as applicable, of the AllianceBernstein International Discovery Equity Portfolio, the Class A, Class C, Advisor Class, Class R, Class K and Class I shares, as applicable, of the AllianceBernstein International Focus 40 Portfolio, the Class A, Class C, Advisor Class, Class R, Class K, Class I, Class 1 and Class 2 shares, as applicable, of the AllianceBernstein Dynamic All Market Fund, the Class A, Class C, Advisor Class, Class R, Class K, Class I, Class 1 and Class 2 shares, as applicable, of the AllianceBernstein Dynamic All Market Plus Fund, the Class A, Class C, Advisor Class, Class R, Class K and Class I shares, as applicable, of the AllianceBernstein Emerging Markets Multi-Asset Portfolio, the Class A, Class C, Advisor Class, Class R, Class K, Class I, Class 1 and Class 2 shares, as applicable, of the AllianceBernstein Select US Equity Portfolio, the Class A, Class C, Advisor Class, Class R, Class K, Class I, Class 1 and Class 2 shares, as applicable, of the AllianceBernstein Emerging Markets Equity Portfolio and the Class 1 and Class 2 shares, as applicable, of the AllianceBernstein Select US Long/Short Portfolio is amended or superseded.

SIGNATURE

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 and State of New York, on the 21^st day of December, 2012.

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

Pursuant to the requirements of the Securities Act of l933, as amended, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated:

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

AllianceBernstein Select US Long/Short Portfolio

SUMMARY INFORMATION

ALLIANCEBERNSTEIN SELECT US LONG/SHORT PORTFOLIO

INVESTMENT OBJECTIVE

The Fund’s investment objective is long-term growth of capital.

FEES AND EXPENSES OF THE FUND

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 Fund--Sales Charge Reduction Programs for Class A Shares on page 18 of this Prospectus and in Purchase of Shares--Sales Charge Reduction Programs for Class A Shares on page 65 of the Fund’s Statement of Additional Information (“SAI”).

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees AllianceBernstein Select US Long/Short Portfolio (USD $)	CLASS A SHARES		CLASS C SHARES		ADVISOR CLASS SHARES	CLASS R SHARES	CLASS K SHARES	CLASS I SHARES
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	4.25%		none		none	none	none	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	1.00%	[2]	none	none	none	none
Exchange Fee	none		none		none	none	none	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage
of the value of your investment)

Annual Fund Operating Expenses AllianceBernstein Select US Long/Short Portfolio		CLASS A	CLASS C	ADVISOR CLASS	CLASS R	CLASS K	CLASS I
Management Fees		1.70%	1.70%	1.70%	1.70%	1.70%	1.70%
Distribution and/or Service (12b-1) Fees		0.30%	1.00%	none	0.50%	0.25%	none
Other Expenses: Transfer Agent		0.10%	0.12%	0.10%	0.26%	0.20%	0.12%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short		0.56%	0.56%	0.56%	0.56%	0.56%	0.56%
Other Expenses		0.66%	0.66%	0.66%	0.66%	0.66%	0.66%
Total Other Expenses	[1]	1.32%	1.34%	1.32%	1.48%	1.42%	1.34%
Total Annual Fund Operating Expenses		3.32%	4.04%	3.02%	3.68%	3.37%	3.04%
Fee Waiver and/or Expense Reimbursement	[2]	(0.51%)	(0.53%)	(0.51%)	(0.67%)	(0.61%)	(0.53%)
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement		2.81%	3.51%	2.51%	3.01%	2.76%	2.51%

EXAMPLES

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, that the Fund’s operating expenses stay the same and that the fee waiver remains in effect as agreed upon. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example AllianceBernstein Select US Long/Short Portfolio (USD $)	CLASS A	CLASS C		ADVISOR CLASS	CLASS R	CLASS K	CLASS I
After 1 Year	697	354	[1]	254	304	279	254
After 3 Years	1,259	1,077		782	930	856	782

PORTFOLIO TURNOVER

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. The Fund is expected to have a very high portfolio turnover rate.

PRINCIPAL STRATEGIES

Under normal circumstances, the Fund invests at least 80% of its net assets in equity securities of U.S. companies, short positions in such securities, and cash and U.S. cash equivalents.

The Adviser selects investments for the Fund’s long positions through an intensive “bottom-up” approach that places an emphasis on companies that are engaged in business activities with solid long-term growth potential and high barriers to entry, that have strong cash flows and other financial metrics, and that have transparent financial statements and business models. The Adviser also evaluates the quality of company management based on a series of criteria, including: (1) management’s focus on shareholder returns, such as through a demonstrated commitment to dividends and dividend growth, share buybacks or other shareholder-friendly corporate actions; (2) management’s employment of conservative accounting methodologies; (3) management incentives, such as direct equity ownership; and (4) management accessibility. The Adviser seeks to identify companies where events or catalysts may drive the company’s share price higher, such as earnings and/or revenue growth above consensus forecasts, potential market recognition of undervaluation or overstated market-risk discount, or the institution of any of the shareholder-friendly practices discussed in the preceding sentence. In light of this catalyst-focused approach, the Adviser expects to engage in active and frequent trading for the Fund.

The Adviser may reduce or eliminate the Fund’s holdings in a company’s securities for a number of reasons, including if its evaluation of the above factors changes adversely, if the anticipated events or catalysts do not occur or do not affect the price of the securities as expected, or if the anticipated events or catalysts do occur and cause the securities to be, in the Adviser’s view, overvalued or fully valued. At any given time the Fund may emphasize growth stocks over value stocks, or vice versa.

In determining securities to be sold short, the Adviser looks for companies facing near-term difficulties such as high valuations, quality of earnings issues, or weakness in demand due to economic factors or long-term issues such as changing technology or competitive concerns in their industries. The Fund may also sell securities of exchange-traded funds, or ETFs, short, including to hedge its exposure to specific market sectors or if it believes a specific sector or asset will decline in value. When the Fund sells securities short, it sells a stock that it does not own (but has borrowed) at its current market price in anticipation that the price of the stock will decline. To complete, or close out, the short sale transaction, the Fund buys the same stock in the market at a later date and returns it to the lender.

The Adviser derives the ratio between long and short positions for the Fund based on its bottom-up analysis supplemented with macro-economic and market analyses. Under normal market conditions, the net long exposure of the Fund (long exposure minus short exposure) will range between 30% and 70%. The Adviser seeks to minimize the variability of Fund returns through industry diversification as well as by managing long and short exposures and/or by holding a material level of cash and/or cash equivalents. For example, the Fund may hold long positions in equity securities with a value equal to 60% of its net assets and have short sale obligations equal to 15% of its net assets, resulting in 45% net long exposure. Assuming a 60% long exposure, 40% of Fund assets will be held in cash or cash equivalents, including cash and cash equivalents held to cover the Fund’s short sale obligations. During periods of excessive market risk, the Adviser may reduce the net long exposure of the Fund. The Fund may at times hold long and short positions that in the aggregate exceed the value of its net assets (i.e., so that the Fund is effectively leveraged).

The Fund’s investments will be focused on securities of companies with large and medium market capitalizations, but it may also take long and short positions in securities of small-capitalization companies. The Fund may invest in non-U.S. companies, but currently intends to limit its investments in such companies to no more than 10% of its net assets. The Fund may purchase securities in initial public offerings and expects to do so on a regular basis.

The Fund may enter into derivatives transactions, such as options, futures contracts, forwards, and swaps, as part of its investment strategies or for hedging or other risk management purposes. These transactions may be used, for example, as a means to take a short position in a security or sector without actually selling securities short.

PRINCIPAL RISKS

• MARKET RISK: The value of the Fund’s assets will fluctuate as the stock, bond or currency markets fluctuate. The value of the Fund’s investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market.

• SHORT SALE RISK: Short sales involve the risk that the Fund will incur a loss by subsequently buying a security at a higher price than the price at which it sold the security. The amount of such loss is theoretically unlimited, as it will be based on the increase in value of the security sold short. In contrast, the risk of loss from a long position is limited to the Fund’s investment in the security, because the price of the security cannot fall below zero. The Fund may not always be able to close out a short position on favorable terms.

• DERIVATIVES RISK: 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.

• LEVERAGE RISK: To the extent the Fund uses leveraging techniques, the value of its shares may be more volatile because leverage tends to exaggerate the effect of any increase or decrease in the value of the Fund’s investments.

• CAPITALIZATION RISK: Investments in small- and mid-capitalization companies may be more volatile than investments in large-capitalization companies. Investments in these companies may have additional risks because these companies may have limited product lines, markets or financial resources.

• DIVERSIFICATION RISK: The Fund may have more risk because it is “non-diversified”, meaning that it can invest more of its assets in a smaller number of issuers. Accordingly, changes in the value of a single security may have a more significant effect, either negative or positive, on the Fund’s net asset value, or NAV.

• ACTIVE TRADING RISK: The Fund expects to engage in active and frequent trading of its portfolio securities and its portfolio turnover rate is expected to greatly exceed 100%. A higher rate of portfolio turnover increases transaction costs, which may negatively affect the Fund’s return. In addition, a high rate of portfolio turnover may result in substantial short-term gains, which may have adverse tax consequences for Fund shareholders.

• 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, 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.

PERFORMANCE INFORMATION

No performance information is available for the Fund because it has not yet been in operation for a full calendar year.

[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 contingent deferred sales charge ("CDSC"), which may be subject to waiver in certain circumstances.

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

[1] Total Other Expenses are based on estimated amounts for the current fiscal year.

[2] The Adviser has agreed to waive its management fees and/or to bear expenses of the Fund through December 12, 2015 to the extent necessary to prevent total Fund operating expenses (excluding expenses associated with securities sold short, acquired fund fees and expenses other than the advisory fees of any AllianceBernstein Mutual Funds in which the Fund may invest, interest expense, taxes, extraordinary expenses, and brokerage commissions and other transaction costs), on an annualized basis, from exceeding 2.25%, 2.95%, 1.95%, 2.45%, 2.20% and 1.95% of average daily net assets, respectively, for Class A, Class C, Advisor Class, Class R, Class K and Class I shares ("expense limitations"). Any fees waived and expenses borne by the Adviser may be reimbursed by the Fund until December 12, 2015, provided that no reimbursement payment will be made that would cause the Fund's Total Annual Fund Operating Expenses to exceed the expense limitations or cause the total of the payments to exceed the Fund's total initial offering expenses.

[1] Assuming redemption at the end of the period, a 1% CDSC would increase the expenses by approximately $100.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN CAP FUND, INC.
Prospectus Date	rr_ProspectusDate	Dec. 04, 2012
AllianceBernstein Select US Long/Short Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	SUMMARY INFORMATION ALLIANCEBERNSTEIN SELECT US LONG/SHORT PORTFOLIO
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 Fund--Sales Charge Reduction Programs for Class A Shares on page 18 of this Prospectus and in Purchase of Shares--Sales Charge Reduction Programs for Class A Shares on page 65 of the Fund’s Statement of Additional Information (“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)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 12, 2015
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. The Fund is expected to have a very high portfolio turnover rate.
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
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Total Other Expenses are based on estimated amounts for the current fiscal year.
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, that the Fund’s operating expenses stay the same and that the fee waiver remains in effect as agreed upon. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets in equity securities of U.S. companies, short positions in such securities, and cash and U.S. cash equivalents. The Adviser selects investments for the Fund’s long positions through an intensive “bottom-up” approach that places an emphasis on companies that are engaged in business activities with solid long-term growth potential and high barriers to entry, that have strong cash flows and other financial metrics, and that have transparent financial statements and business models. The Adviser also evaluates the quality of company management based on a series of criteria, including: (1) management’s focus on shareholder returns, such as through a demonstrated commitment to dividends and dividend growth, share buybacks or other shareholder-friendly corporate actions; (2) management’s employment of conservative accounting methodologies; (3) management incentives, such as direct equity ownership; and (4) management accessibility. The Adviser seeks to identify companies where events or catalysts may drive the company’s share price higher, such as earnings and/or revenue growth above consensus forecasts, potential market recognition of undervaluation or overstated market-risk discount, or the institution of any of the shareholder-friendly practices discussed in the preceding sentence. In light of this catalyst-focused approach, the Adviser expects to engage in active and frequent trading for the Fund. The Adviser may reduce or eliminate the Fund’s holdings in a company’s securities for a number of reasons, including if its evaluation of the above factors changes adversely, if the anticipated events or catalysts do not occur or do not affect the price of the securities as expected, or if the anticipated events or catalysts do occur and cause the securities to be, in the Adviser’s view, overvalued or fully valued. At any given time the Fund may emphasize growth stocks over value stocks, or vice versa. In determining securities to be sold short, the Adviser looks for companies facing near-term difficulties such as high valuations, quality of earnings issues, or weakness in demand due to economic factors or long-term issues such as changing technology or competitive concerns in their industries. The Fund may also sell securities of exchange-traded funds, or ETFs, short, including to hedge its exposure to specific market sectors or if it believes a specific sector or asset will decline in value. When the Fund sells securities short, it sells a stock that it does not own (but has borrowed) at its current market price in anticipation that the price of the stock will decline. To complete, or close out, the short sale transaction, the Fund buys the same stock in the market at a later date and returns it to the lender. The Adviser derives the ratio between long and short positions for the Fund based on its bottom-up analysis supplemented with macro-economic and market analyses. Under normal market conditions, the net long exposure of the Fund (long exposure minus short exposure) will range between 30% and 70%. The Adviser seeks to minimize the variability of Fund returns through industry diversification as well as by managing long and short exposures and/or by holding a material level of cash and/or cash equivalents. For example, the Fund may hold long positions in equity securities with a value equal to 60% of its net assets and have short sale obligations equal to 15% of its net assets, resulting in 45% net long exposure. Assuming a 60% long exposure, 40% of Fund assets will be held in cash or cash equivalents, including cash and cash equivalents held to cover the Fund’s short sale obligations. During periods of excessive market risk, the Adviser may reduce the net long exposure of the Fund. The Fund may at times hold long and short positions that in the aggregate exceed the value of its net assets (i.e., so that the Fund is effectively leveraged). The Fund’s investments will be focused on securities of companies with large and medium market capitalizations, but it may also take long and short positions in securities of small-capitalization companies. The Fund may invest in non-U.S. companies, but currently intends to limit its investments in such companies to no more than 10% of its net assets. The Fund may purchase securities in initial public offerings and expects to do so on a regular basis. The Fund may enter into derivatives transactions, such as options, futures contracts, forwards, and swaps, as part of its investment strategies or for hedging or other risk management purposes. These transactions may be used, for example, as a means to take a short position in a security or sector without actually selling securities short.
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, bond or currency markets fluctuate. The value of the Fund’s investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. SHORT SALE RISK: Short sales involve the risk that the Fund will incur a loss by subsequently buying a security at a higher price than the price at which it sold the security. The amount of such loss is theoretically unlimited, as it will be based on the increase in value of the security sold short. In contrast, the risk of loss from a long position is limited to the Fund’s investment in the security, because the price of the security cannot fall below zero. The Fund may not always be able to close out a short position on favorable terms. DERIVATIVES RISK: 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. LEVERAGE RISK: To the extent the Fund uses leveraging techniques, the value of its shares may be more volatile because leverage tends to exaggerate the effect of any increase or decrease in the value of the Fund’s investments. CAPITALIZATION RISK: Investments in small- and mid-capitalization companies may be more volatile than investments in large-capitalization companies. Investments in these companies may have additional risks because these companies may have limited product lines, markets or financial resources. DIVERSIFICATION RISK: The Fund may have more risk because it is “non-diversified”, meaning that it can invest more of its assets in a smaller number of issuers. Accordingly, changes in the value of a single security may have a more significant effect, either negative or positive, on the Fund’s net asset value, or NAV. ACTIVE TRADING RISK: The Fund expects to engage in active and frequent trading of its portfolio securities and its portfolio turnover rate is expected to greatly exceed 100%. A higher rate of portfolio turnover increases transaction costs, which may negatively affect the Fund’s return. In addition, a high rate of portfolio turnover may result in substantial short-term gains, which may have adverse tax consequences for Fund shareholders. 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, 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.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	DIVERSIFICATION RISK: The Fund may have more risk because it is “non-diversified”, meaning that it can invest more of its assets in a smaller number of issuers. Accordingly, changes in the value of a single security may have a more significant effect, either negative or positive, on the Fund’s net asset value, or NAV.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	No performance information is available for the Fund because it has not yet been in operation for a full calendar year.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	No performance information is available for the Fund because it has not yet been in operation for a full calendar year.
AllianceBernstein Select US Long/Short Portfolio | 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	1.70%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.30%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.10%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short	rr_Component2OtherExpensesOverAssets	0.56%
Other Expenses	rr_Component3OtherExpensesOverAssets	0.66%
Total Other Expenses	rr_OtherExpensesOverAssets	1.32%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.32%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.51%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	2.81%
After 1 Year	rr_ExpenseExampleYear01	697
After 3 Years	rr_ExpenseExampleYear03	1,259
AllianceBernstein Select US Long/Short Portfolio | 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	1.70%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.12%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short	rr_Component2OtherExpensesOverAssets	0.56%
Other Expenses	rr_Component3OtherExpensesOverAssets	0.66%
Total Other Expenses	rr_OtherExpensesOverAssets	1.34%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	4.04%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.53%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	3.51%
After 1 Year	rr_ExpenseExampleYear01	354	[5]
After 3 Years	rr_ExpenseExampleYear03	1,077
AllianceBernstein Select US Long/Short Portfolio | 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	1.70%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.10%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short	rr_Component2OtherExpensesOverAssets	0.56%
Other Expenses	rr_Component3OtherExpensesOverAssets	0.66%
Total Other Expenses	rr_OtherExpensesOverAssets	1.32%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.02%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.51%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	2.51%
After 1 Year	rr_ExpenseExampleYear01	254
After 3 Years	rr_ExpenseExampleYear03	782
AllianceBernstein Select US Long/Short Portfolio | 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	1.70%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.26%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short	rr_Component2OtherExpensesOverAssets	0.56%
Other Expenses	rr_Component3OtherExpensesOverAssets	0.66%
Total Other Expenses	rr_OtherExpensesOverAssets	1.48%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.68%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.67%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	3.01%
After 1 Year	rr_ExpenseExampleYear01	304
After 3 Years	rr_ExpenseExampleYear03	930
AllianceBernstein Select US Long/Short Portfolio | 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	1.70%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.20%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short	rr_Component2OtherExpensesOverAssets	0.56%
Other Expenses	rr_Component3OtherExpensesOverAssets	0.66%
Total Other Expenses	rr_OtherExpensesOverAssets	1.42%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.37%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.61%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	2.76%
After 1 Year	rr_ExpenseExampleYear01	279
After 3 Years	rr_ExpenseExampleYear03	856
AllianceBernstein Select US Long/Short Portfolio | 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	1.70%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.12%
Other Expenses: Dividend Expense, Borrowing Costs and Brokerage Expense on Securities Sold Short	rr_Component2OtherExpensesOverAssets	0.56%
Other Expenses	rr_Component3OtherExpensesOverAssets	0.66%
Total Other Expenses	rr_OtherExpensesOverAssets	1.34%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.04%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.53%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	2.51%
After 1 Year	rr_ExpenseExampleYear01	254
After 3 Years	rr_ExpenseExampleYear03	782

[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 contingent deferred sales charge ("CDSC"), which may be subject to waiver in certain circumstances.

[2] Total Other Expenses are based on estimated amounts for the current fiscal year.

[3] The Adviser has agreed to waive its management fees and/or to bear expenses of the Fund through December 12, 2015 to the extent necessary to prevent total Fund operating expenses (excluding expenses associated with securities sold short, acquired fund fees and expenses other than the advisory fees of any AllianceBernstein Mutual Funds in which the Fund may invest, interest expense, taxes, extraordinary expenses, and brokerage commissions and other transaction costs), on an annualized basis, from exceeding 2.25%, 2.95%, 1.95%, 2.45%, 2.20% and 1.95% of average daily net assets, respectively, for Class A, Class C, Advisor Class, Class R, Class K and Class I shares ("expense limitations"). Any fees waived and expenses borne by the Adviser may be reimbursed by the Fund until December 12, 2015, provided that no reimbursement payment will be made that would cause the Fund's Total Annual Fund Operating Expenses to exceed the expense limitations or cause the total of the payments to exceed the Fund's total initial offering expenses.

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

[5] Assuming redemption at the end of the period, a 1% CDSC would increase the expenses by approximately $100.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN CAP FUND, INC.
Prospectus Date	rr_ProspectusDate	Dec. 04, 2012
Document Creation Date	dei_DocumentCreationDate	Dec. 11, 2012

XML

Document and Entity Information	12 Months Ended
	Dec. 04, 2012
Risk/Return:
Document Type	485BPOS
Document Period End Date	Dec. 11, 2012
Registrant Name	ALLIANCEBERNSTEIN CAP FUND, INC.
Central Index Key	0000081443
Amendment Flag	false
Document Creation Date	Dec. 11, 2012
Document Effective Date	Dec. 11, 2012
Prospectus Date	Dec. 04, 2012