SC 13D/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C.  20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 5)

Quicksilver Resources, Inc.

(Name of Issuer)

Common Stock

(Title of class of securities)

74837R-10-4

(CUSIP number)

Anne Darden Self

801 Cherry Street

Suite 3700, Unit 19

Forth Worth, Texas 76102

(817) 665-5008

(Name, address and telephone number of person authorized to receive notices and communications)

October 24, 2010

(Date of event which requires filing of this statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box  ¨.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (the “Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 74837R-10-4 13D Page 2

1.	NAME OF REPORTING PERSON: Quicksilver Energy, L.P.
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:			(a)   ¨ (b)  x
3.	SEC USE ONLY
4.	SOURCE OF FUNDS:		OO and WC
5.	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e):					¨
6.	CITIZENSHIP OR PLACE OF ORGANIZATION:			Texas
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7.	SOLE VOTING POWER:		41,677,288 (1)
	8.	SHARED VOTING POWER:		0
	9.	SOLE DISPOSITIVE POWER:		41,677,288 (1)
	10.	SHARED DISPOSITIVE POWER:		0
11.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:			41,677,288 (1)
12.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:				¨
13.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):			24.5%
14.	TYPE OF REPORTING PERSON:			PN

(1)           Power is exercised through its sole general partner, Pennsylvania Management, LLC.

CUSIP No. 74837R-10-4 13D Page 3

1.	NAME OF REPORTING PERSON: Pennsylvania Management, LLC
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:			(a)   ¨ (b)  x
3.	SEC USE ONLY
4.	SOURCE OF FUNDS:		OO and WC
5.	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e):				¨
6.	CITIZENSHIP OR PLACE OF ORGANIZATION:			Texas
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7.	SOLE VOTING POWER:		41,677,288 (1)(2)
	8.	SHARED VOTING POWER:		0
	9.	SOLE DISPOSITIVE POWER:		41,677,288 (1)(2)
	10.	SHARED DISPOSITIVE POWER:		0
11.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:			41,677,288 (1)(2)
12.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:				¨
13.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):			24.5%
14.	TYPE OF REPORTING PERSON:			OO (limited liability company)

(1)        Power is exercised as sole general partner of Quicksilver Energy, L.P.

(2)        Power is exercised though its three members: Glenn Darden, Thomas F. Darden and Anne Darden Self.

CUSIP No. 74837R-10-4 13D Page 4

1.	NAME OF REPORTING PERSON: Glenn Darden
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:			(a)   ¨ (b)  x
3.	SEC USE ONLY
4.	SOURCE OF FUNDS:		PF and Not Applicable
5.	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e):				¨
6.	CITIZENSHIP OR PLACE OF ORGANIZATION:			USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7.	SOLE VOTING POWER:		3,597,811 (1)(2)(3)
	8.	SHARED VOTING POWER:		41,677,288 (4)
	9.	SOLE DISPOSITIVE POWER:		3,263,991 (1)(2)
	10.	SHARED DISPOSITIVE POWER:		41,677,288 (4)
11.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:			45,275,099 (1)(2)(3)(4)
12.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:					¨
13.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):			26.6%
14.	TYPE OF REPORTING PERSON:			IN

(1) Includes 162,534 shares subject to options that were vested or will vest within 60 days following October 15, 2010.

(2) Includes 32,594 shares represented by units Mr. Darden holds in a Unitized Stock Fund through Quicksilver Resources Inc.’s 401(k) as disclosed in QRI’s Proxy Statement filed with the Securities and Exchange Commission on April 7, 2010.

(3) Includes 333,820 shares of unvested restricted stock as of October 15, 2010.

(4) Represents or includes 41,677,288 shares owned by Quicksilver Energy, L.P., such shares beneficially owned by Mr. Darden solely in his capacity as a member of Pennsylvania Management, LLC, the sole general partner of Quicksilver Energy, L.P.  Mr. Darden disclaims beneficial ownership of the 41,677,288 shares owned by Quicksilver Energy, L.P., except to the extent of his pecuniary interest in them arising from his ownership interest as a limited partner of Quicksilver Energy, L.P., as a shareholder of Mercury Production Company, another limited partner of Quicksilver Energy, L.P. and as a member of Pennsylvania Management, LLC.

CUSIP No. 74837R-10-4 13D Page 5

1.	NAME OF REPORTING PERSON: Thomas F. Darden
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:			(a)   ¨ (b)  x
3.	SEC USE ONLY
4.	SOURCE OF FUNDS:		PF and Not Applicable
5.	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e):				¨
6.	CITIZENSHIP OR PLACE OF ORGANIZATION:			USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7.	SOLE VOTING POWER:		3,713,307 (1)(2)(3)
	8.	SHARED VOTING POWER:		41,677,288 (4)
	9.	SOLE DISPOSITIVE POWER:		3,379,487 (1)(2)
	10.	SHARED DISPOSITIVE POWER:		41,677,288 (4)
11.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:			45,390,595 (1)(2)(3)(4)
12.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:					¨
13.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):			26.6%
14.	TYPE OF REPORTING PERSON:			IN

(1) Includes 162,534 shares subject to options that were vested or that will vest within 60 days following October 15, 2010.

(2) Includes 100,660 shares represented by units Mr. Darden holds in a Unitized Stock Fund through Quicksilver Resources Inc.’s 401(k) as disclosed in QRI’s Proxy Statement filed with the Securities and Exchange Commission on April 7, 2010.

(3) Includes 333,820 shares of unvested restricted stock as of October 15, 2010.

(4) Represents or includes 41,677,288 shares owned by Quicksilver Energy, L.P., such shares beneficially owned by Mr. Darden solely in his capacity as a member of Pennsylvania Management, LLC, the sole general partner of Quicksilver Energy, L.P.  Mr. Darden disclaims beneficial ownership of the 41,677,288 shares owned by Quicksilver Energy, L.P., except to the extent of his pecuniary interest in them arising from his ownership interest as a limited partner of Quicksilver Energy, L.P., as a shareholder of Mercury Production Company, another limited partner of Quicksilver Energy, L.P. and as a member of Pennsylvania Management, LLC.

CUSIP No. 74837R-10-4 13D Page 6

1.	NAME OF REPORTING PERSON: Anne Darden Self
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:			(a)   ¨ (b)  x
3.	SEC USE ONLY
4.	SOURCE OF FUNDS:		PF and Not Applicable
5.	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM2(d) OR 2(e):				¨
6.	CITIZENSHIP OR PLACE OF ORGANIZATION:			USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7.	SOLE VOTING POWER:		2,254,609 (1)(2)(3)
	8.	SHARED VOTING POWER:		41,677,288 (4)
	9.	SOLE DISPOSITIVE POWER:		2,225,944 (1)(2)
	10.	SHARED DISPOSITIVE POWER:		41,677,288 (4)
11.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:			43,931,897 (1)(2)(3)(4)
12.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES:					¨
13.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):			25.8%
14.	TYPE OF REPORTING PERSON:			IN

(1) Includes 20,833 shares subject to options that were vested or that will vest within 60 days following October 15, 2010.

(2) Includes 52,020 shares represented by units Ms. Self holds in a Unitized Stock Fund through Quicksilver Resources Inc.’s 401(k) as disclosed in QRI’s Proxy Statement filed with the Securities and Exchange Commission on April 7, 2010.

(3) Includes 28,665 shares of unvested restricted stock as of October 15, 2010.

(4) Represents or includes 41,677,288 shares owned by Quicksilver Energy, L.P., such shares beneficially owned by Ms. Self solely in her capacity as a member of Pennsylvania Management, LLC, the sole general partner of Quicksilver Energy, L.P.  Ms. Self disclaims beneficial ownership of the 41,677,288 shares owned by Quicksilver Energy, L.P., except to the extent of her pecuniary interest in them arising from her ownership interest as a limited partner of Quicksilver Energy, L.P., as a shareholder of Mercury Production Company, another limited partner of Quicksilver Energy, L.P. and as a member of Pennsylvania Management, LLC.

This Amendment No. 5 to Schedule 13D (this “Amendment No. 5”) amends and supplements: (i) a statement on Schedule 13D filed by Quicksilver Energy, L.P. on March 12, 1999, (ii) statements on Schedule 13D filed by Mercury Exploration Company, Glenn Darden, Thomas F. Darden and Anne Darden Self on March 12, 1999, as each such statement was amended on January 21, 2000, September 24, 2007 and January 9, 2009 (“Amendment No. 3”) and (iii) a statement on Schedule 13D filed by Quicksilver Energy, L.P., Pennsylvania Management, LLC, Glenn Darden, Thomas F. Darden and Anne Darden Self on October 18, 2010 (“Amendment No. 4”) (as so amended, the “Schedule 13D”).

All terms used in this Amendment No. 5, but not defined herein, have the meaning given to such terms in Amendment No. 3 or Amendment No. 4, as applicable. The summary descriptions (if any) contained herein of certain agreements and documents are qualified in their entirety by reference to the complete text of such agreements and documents filed as Exhibits hereto or incorporated herein by reference.

Item 4.     Purpose of Transaction.

Item 4 is hereby amended and restated as follows:

The common stock of QRI was acquired and is being held by the Reporting Persons as an investment.  On October 15, 2010, QELP, Glenn Darden, Thomas F. Darden and Anne Darden Self (collectively the “Darden Family Interests”) sent a letter to the board of directors of QRI.  In the letter, the Darden Family Interests formally notified the directors of their interest in exploring strategic alternatives for QRI, which could include, among other things, a possible take private transaction of QRI by the Darden Family Interests.  The Darden Family Interests stated, in the letter, that while they were not in a position to provide the directors with their valuation of QRI at this time, and that there could be no assurance that a take private proposal by them would be forthcoming, they were fully aware and wo uld expect that any such proposal made by them would involve a substantial premium to the current market price.  In the letter, the Darden Family Interests also requested that the directors amend QRI’s rights plan, so that the Darden Family Interests and another major stockholder, who had indicated a similar interest to the directors, SPO Partners & Co. (“SPO”), could discuss strategic alternatives for QRI.  In addition, the Darden Family Interests asked for permission to share, subject to a customary nondisclosure agreement, certain nonpublic information of QRI with any financial advisors that they retained.

On October 24, 2010, the Darden Family Interests entered into a Confidentiality Agreement with QRI pursuant to which (i) QRI will make available to the Darden Family Interests certain nonpublic information regarding QRI and (ii) the Darden Family Interests agreed not to acquire additional shares of common stock of QRI for the six (6) month period following the date of the Confidentiality Agreement.  In addition, on October 24, 2010, the transaction committee of the board of directors of QRI advised the Darden Family Interests that it did not intend to amend QRI’s rights plan to permit discussions between SPO and the Darden Family Interests at this time.

Item 7.     Material to be Filed as Exhibits.

Exhibit A	Joint Filing Statement (filed herewith).
Exhibit 99.1	Confidentiality Agreement, dated October 24, 2010, by and between Quicksilver Energy, L.P.and Quicksilver Resources Inc.

7

SIGNATURES

After reasonable inquiry and to the best of the knowledge and belief of the undersigned, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated:  October 25, 2010
	QUICKSILVER ENERGY, L.P.
	By:	PENNSYLVANIA MANAGEMENT, LLC, its general partner
	By:	/s/  Glenn Darden
	Name:	Glenn Darden
	Title:	Manager

PENNSYLVANIA MANAGEMENT, LLC
By:	/s/  Glenn Darden
Name:	Glenn Darden
Title:	Manager

  /s/  Glenn Darden

Glenn Darden

  /s/  Thomas F. Darden

Thomas F. Darden

  /s/  Anne Darden Self

Anne Darden Self

Exhibit A

Joint Filing Statement

We, the undersigned, hereby express our agreement that the attached Schedule 13D is, and any further amendments thereto signed by each of the undersigned shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934. This agreement may be terminated with respect to the obligations to jointly file future amendments to such statement on Schedule 13D as to any of the undersigned upon such person giving written notice thereof to each of the other persons signatory hereto, at the principal office thereof.

Dated:  October 25, 2010
	QUICKSILVER ENERGY, L.P.
	By:	PENNSYLVANIA MANAGEMENT, LLC, its general partner
	By:	/s/  Glenn Darden
	Name:	Glenn Darden
	Title:	Manager

PENNSYLVANIA MANAGEMENT, LLC
By:	/s/  Glenn Darden
Name:	Glenn Darden
Title:	Manager

  /s/  Glenn Darden

Glenn Darden

  /s/  Thomas F. Darden

Thomas F. Darden

  /s/  Anne Darden Self

Anne Darden Self

EX-99.1

EXHIBIT 99.1

QUICKSILVER RESOURCES INC.

October 24, 2010

Quicksilver Energy L.P.

801 Cherry Street

Suite 3700, Unit 19

Fort Worth, Texas  76102

Ladies and Gentlemen:

It is expected that Quicksilver Resources Inc. (the “Company”) and its Representatives (as defined below) will furnish you and your Representatives with, or otherwise make available to you and your Representatives, certain information about the business, operations and affairs of the Company and its subsidiaries.  Such information (whether oral, written, electronic or otherwise and whether provided before, on or after the date of this agreement), regardless of the form in which it is provided or maintained and whether prepared by the Company, its Representatives or otherwise, together with any notes, analyses, compilations, studies, interpretations or other documents prepared by you or your Representatives which contain or otherwise reflect such information, is hereinafter referred to as “Confidential Information,” except that “Confidential Information” does not include any information that (i) was publicly available prior to the date of this agreement or hereafter becomes publicly available without any violation of this agreement on the part of you or any of your Representatives, or (ii) becomes available to you from a person other than the Company and its Representatives who is not, to the best of your knowledge, subject to any contractual, legal, fiduciary or other obligation to keep such information confidential.  As used in this agreement, “person” means an individual or entity and the “Representatives” of any person means the affiliates, officers, directors, employees, attorneys, accountants, financial or other advisors and other agents and representatives of such person; provided that  “Representatives” shall not include any prospective sources of financing (whether equity or debt financing).  For the avoidance of doubt, no Confidential Information shall be provided by you or your Representatives to any prospective sources of financing (whether equity or debt financing) without, in each case, prior written consent of the Committee; provided, that with respect to any major national or international bank that will serve as a bona fide debt provider, your obligation is limited to treating such Person as a Representative hereunder (including by requiring execution of an appropriate confidentialit y agreement) and to notifying the Committee of the identity of such Person.

Quicksilver Energy L.P. October 24, 2010

In consideration of your being provided with Confidential Information, you agree to comply with the terms of this agreement.

You agree that all Confidential Information will be kept confidential and will not be disclosed, in whole or in part, by you or any of your Representatives to any person other than those of your Representatives who need to know such Confidential Information for the purpose of evaluating the Company on your behalf; provided that (i) you will require your Representatives to be bound by the terms of this agreement applicable to them to the fullest extent as if they were parties hereto and (ii) you will be responsible for any breach of this agreement by you or any of your Representatives.

Without the prior written consent of the Transaction Committee of Board of Directors (the “Committee”), you agree that none of you or any of your Representatives will disclose to any person the fact that any Confidential Information has been made available to you or your Representatives, that discussions or negotiations are taking place with the Committee, or any of the terms, conditions or other facts with respect to such discussions or negotiations, including the status thereof, except as otherwise required by law or the applicable rules of any national securities exchange.

You agree that unless otherwise directed by the Committee in writing (i) all communications with the Company regarding requests for Confidential Information, (ii) requests for additional information, facility tours, or management meetings, and (iii) discussions or questions regarding procedures with respect to the Confidential Information, will be submitted or directed by you or your Representatives only to a person or persons designated in writing by the Committee.

You agree that none of your Representatives will use or allow the use of any Confidential Information for any purpose except to assist you.

Promptly following your receipt of a request from the Committee, you and your Representatives shall, at your election,  either destroy or return to the Company all Confidential Information provided to you or your Representatives hereunder, except for that portion of the Confidential Information that consists of analyses, compilations, studies or other documents prepared by you or your Representatives.  Any such portion of the Confidential Information that consists of analyses, compilations, studies or other documents prepared by you or your Representatives will, to the extent legally permitted, be destroyed immediately upon the Committee’s request.  Upon the request of the Committee, you will provide the Committee with prompt written certification of your and your Represen tatives’ compliance with the preceding two sentences.

If you or anyone to whom you transmit the Confidential Information is requested or required by applicable law (by oral questions, interrogatories, requests for information

Quicksilver Energy L.P. October 24, 2010

or documents, subpoenas, civil investigative demand or similar process) to disclose any of the Confidential Information, you will provide the Company and the Committee with prompt written notice so that the Company may seek a protective order or other appropriate remedy and/or waive compliance with the provisions of this agreement, and you will use your reasonable best efforts to assist the Company in seeking such protective order.  If such protective order or other remedy is not obtained, or the Committee waives your compliance with the provisions of this agreement, you or your Representatives will furnish only that portion of the Confidential Information that is legally required to be furnished, in the opinion of your counsel, and will exercise your reasonable best efforts to obtain a protect ive order or other reliable assurance that confidential treatment will be accorded to the Confidential Information.

You hereby acknowledge that, in your examination of the Confidential Information, you will receive material nonpublic information concerning the Company, and that you are aware (and that your Representatives have been or will be advised by you) that the United States securities laws restrict the purchase and sale of securities by persons who possess certain nonpublic information relating to the issuer of such securities.  You agree that for a period of six months following the date hereof, none of you and any of your affiliates (and any person acting on behalf of or in concert with you or any of your affiliates) will, directly or indirectly, without the Company’s prior written consent, acquire or agree to acquire any securities of the Company.

No failure or delay by the Company in exercising any right, power or privilege hereunder shall operate as a waiver thereof or preclude any other or further exercise thereof or the exercise of any other right, power or privilege hereunder.

You agree that the Company would be irreparably injured by a breach of this agreement by you or your Representatives and that, in such event (or in the event the Committee reasonably believes such event is reasonably likely to occur), the Company shall be entitled, in addition to any and all other remedies, to injunctive relief and specific performance without the necessity of providing any bond or other security, and you hereby irrevocably consent to such relief.

If any term or provision of this agreement or any application hereof shall be invalid and unenforceable, the remainder of this agreement and any other application of such term or provision shall not be affected thereby.

This agreement may be modified or waived only by an instrument signed by the parties hereto.  This agreement may not be assigned by any party hereto without the express prior written consent of the other party hereto, and any assignment of this agreement by either party without the prior written consent of the other shall be void.

Quicksilver Energy L.P. October 24, 2010

This agreement shall be governed by, and construed in accordance with, the laws of the State of New York without regard to its conflict of law provisions.  You hereby irrevocably and unconditionally submit to the exclusive jurisdiction of any state or federal court sitting in New York City, Borough of Manhattan, over any suit, action or proceeding arising out of or relating to this letter agreement.  You hereby agree that service of any process, summons, notice or document by U.S. registered mail addressed to you shall be effective service of process for any such suit, action or proceeding brought against you in any such court.  You hereby irrevocably and unconditionally waive any objection to the laying of venue of any such suit, action or proceeding brought in any such court a nd any claim that any such suit, action or proceeding brought in any such court has been brought in an inconvenient forum.  You agree that a final judgment in any such suit, action or proceeding brought in any such court shall be conclusive and binding upon you and may be enforced in any other courts to whose jurisdiction you are or may be subject by suit upon such judgment.

Except for the preceding two paragraphs, which shall be binding in perpetuity or until the latest date permitted by law, this agreement will be binding upon you and your Representatives for a period of two years from the date hereof.  This agreement may be executed and delivered by facsimile.  Any facsimile signatures shall have the same legal effect as original signatures.

Quicksilver Energy L.P. October 24, 2010

To evidence your agreement with the foregoing, please sign and return a copy of this agreement to the undersigned.

Very truly yours,
QUICKSILVER RESOURCES INC.
By:	/s/  John C. Cirone
	Name:	John C. Cirone
	Title:	Sr. Vice President & General Counsel

Accepted and agreed:

QUICKSILVER ENERGY L.P.
By:	/s/  Glenn Darden
	Name:	Glenn Darden
	Title:	Member