Exhibit 10.1

SECOND AMENDMENT

TO

SECOND AMENDED AND RESTATED

CREDIT AGREEMENT

Dated as of March 4, 2008

AMONG

BILL BARRETT CORPORATION,

AS BORROWER,

THE GUARANTORS,

JPMORGAN CHASE BANK, N.A.

AS ADMINISTRATIVE AGENT,

AND

THE LENDERS PARTY HERETO

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SECOND AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT

AGREEMENT

THIS SECOND AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT (this
“Second Amendment”) dated as of March 4, 2008 is among BILL BARRETT CORPORATION,
a Delaware corporation (the “Borrower”); each of the undersigned guarantors (the
“Guarantors”, and together with the Borrower, the “Obligors”); each of the
lenders party to the Credit Agreement referred to below (collectively, the
“Lenders”); and JPMORGAN CHASE BANK, N.A., as administrative agent for the
Lenders (in such capacity, together with its successors in such capacity, the
“Administrative Agent”).

R E C I T A L S

A. The Borrower, the Agents and the Lenders are parties to that certain Second
Amended and Restated Credit Agreement dated as of March 17, 2006 (as amended by
the First Amendment to Second Amended and Restated Credit Agreement, dated
November 6, 2007, and as further amended, restated, modified or supplemented,
the “Credit Agreement”), pursuant to which the Lenders have made certain credit
available to and on behalf of the Borrower.

B. The Borrower has requested and the Administrative Agent and the Lenders have
agreed to make certain other changes to the Credit Agreement.

C. NOW, THEREFORE, to induce the Agents and the Lenders to enter into this
Second Amendment and in consideration of the premises and the mutual covenants
herein contained, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

Section 1. Defined Terms. Each capitalized term used herein but not otherwise
defined herein has the meaning given such term in the Credit Agreement, as
amended by this Second Amendment. Unless otherwise indicated, all section
references in this Second Amendment refer to sections of the Credit Agreement.

Section 2. Amendments to Credit Agreement.

2.1 Amendments to Section 1.02.

(a) The following definition is hereby added where alphabetically appropriate to
read as follows:

“Second Amendment” means that certain Second Amendment to Second Amended and
Restated Credit Agreement, dated as of March 4, 2008 among the Borrower, the
Guarantors, the Administrative Agent and the Lenders party thereto.

(b) The definition of “Equity Interest” is hereby amended to insert the phrase
“other than any debt securities convertible into any such Equity Interests”
after the phrase “any such Equity Interests” at the end of such definition.

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(c) The definition of “Restricted Payments” is hereby amended to insert the
phrase “other than any debt securities convertible into any such Equity
Interests” after the phrase “any such Equity Interests in the Borrower” at the
end of such definition.

2.2 Amendment to Section 9.02(h)(v) and (vi). Section 9.02(h)(v) and (vi) are
hereby amended and restated in their entirety to read as follows:

“(v) such Permitted Debt does not have a scheduled maturity sooner than the date
which is one year after the Maturity Date, (vi) if such Permitted Debt is
subordinated, then (A) any guarantees thereof will be subordinated and (B) all
terms of subordination are satisfactory to the Administrative Agent and the
Super-Majority Lenders”

2.3 Amendment to Section 9.04(b)(i). Section 9.04(b)(i) is hereby amended and
restated in its entirety to read as follows:

“(i) call, make or offer to make any voluntary or optional Redemption of or
otherwise voluntarily or optionally Redeem (whether in whole or in part) any
Permitted Debt, except (A) to the extent constituting a Redemption, the
conversion of Permitted Debt into common stock of the Borrower and, in
connection therewith, the settlement in cash of any Permitted Debt required to
avoid the issuance of fractional shares of common stock or (B) with the cash
proceeds of (1) an Equity Offering, (2) Permitted Refinancing Debt or (3) any
asset sale to the extent not required by this Agreement to be applied to
repayment of Indebtedness and a concurrent reduction in the Commitments;”

Section 3. Waivers to Credit Agreement.

3.1 Waiver of Section 9.02(h)(i). The Borrower has advised the Administrative
Agent that the Borrower intends to issue certain notes (“Note Issuance”).
Pursuant to Section 9.02(h)(i), the Borrower is required to provide the
Administrative Agent with written notice of the Note Issuance and the amount
thereof and the anticipated closing date, together with copies of certain
documents, not less than ten Business Days prior thereto (the “Notice
Requirement”). The Borrower has notified the Administrative Agent that the
Borrower will not be able to satisfy the Notice Requirement in connection with
the Note Issuance, Accordingly, the Borrower hereby requests, and the Majority
Lenders hereby agree to waive the Notice Requirement with respect to the Note
Issuance; provided, however that such waiver shall only apply to the Notice
Requirement and shall not constitute a waiver of the Borrower’s obligation to
satisfy each other requirement of Section 9.02(h) with respect to the Note
Issuance or any other obligation associated therewith. Except as expressly
waived herein, all covenants, obligations and agreements of the Borrower
contained in the Credit Agreement and the other Loan Documents shall remain in
full force and effect in accordance with their terms.

3.2 Waivers Limited. Except to the extent specifically stated in Section 3.1 of
this Amendment and for no other purpose or period, neither the execution by the
Administrative Agent or the Lenders of this Second Amendment, nor any other act
or omission by the Administrative Agent or the Lenders or their officers in
connection herewith, shall be deemed a

 

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waiver by the Administrative Agent or the Lenders of any other defaults which
may exist, which may have occurred prior to the date hereof, or which may occur
in the future under the Credit Agreement and/or the other Loan Documents, or any
future defaults of the same provision waived hereunder (collectively “Other
Violations”). Similarly, nothing contained in this letter shall directly or
indirectly in any way whatsoever either: (a) impair, prejudice or otherwise
adversely affect the Administrative Agent’s or the Lenders’ right at any time to
exercise any right, privilege or remedy in connection with the Loan Documents
with respect to any Other Violations, (b) amend or alter any provision of the
Credit Agreement, the other Loan Documents, or any other contract or instrument,
or (c) constitute any course of dealing or other basis for altering any
obligation of the Borrower or any right, privilege or remedy of the
Administrative Agent or the Lenders under the Credit Agreement, the other Loan
Documents, or any other contract or instrument. Nothing in this letter shall be
construed to be a consent by the Administrative Agent or the Lenders to any
Other Violations.

Section 4. Conditions Precedent. This Second Amendment shall not become
effective until the date on which each of the following conditions is satisfied
(or waived in accordance with Section 12.02 of the Credit Agreement) (the
“Effective Date”):

4.1 The Administrative Agent shall have received from the Majority Lenders,
counterparts (in such number as may be requested by the Administrative Agent) of
this Second Amendment signed on behalf of such Person.

4.2 No Default shall have occurred and be continuing as of the date hereof,
after giving effect to the terms of this Second Amendment.

4.3 The Administrative Agent shall have received such other documents as the
Administrative Agent or its special counsel may reasonably require.

The Administrative Agent is hereby authorized and directed to declare this
Second Amendment to be effective when it has received documents confirming or
certifying, to the satisfaction of the Administrative Agent, compliance with the
conditions set forth in this Section 4 or the waiver of such conditions as
permitted hereby. Such declaration shall be final, conclusive and binding upon
all parties to the Credit Agreement for all purposes.

Section 5. Miscellaneous.

5.1 Confirmation. The provisions of the Credit Agreement, as amended by this
Second Amendment, shall remain in full force and effect following the
effectiveness of this Second Amendment.

5.2 Ratification and Affirmation; Representations and Warranties. Each Obligor
hereby (a) acknowledges the terms of this Second Amendment; (b) ratifies and
affirms its obligations under, and acknowledges, renews and extends its
continued liability under, each Loan Document to which it is a party and agrees
that each Loan Document to which it is a party remains in full force and effect,
except as expressly amended hereby, notwithstanding the amendments contained
herein and (c) represents and warrants to the Lenders that as of the date
hereof, after giving effect to the terms of this Second Amendment: (i) all of
the representations

 

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and warranties contained in each Loan Document to which it is a party are true
and correct, except to the extent any such representations and warranties are
expressly limited to an earlier date, in which case, such representations and
warranties shall continue to be true and correct as of such specified earlier
date, (ii) no Default or Event of Default has occurred and is continuing and
(iii) no event or events have occurred which individually or in the aggregate
could reasonably be expected to have a Material Adverse Effect.

5.3 Counterparts. This Second Amendment may be executed by one or more of the
parties hereto in any number of separate counterparts, and all of such
counterparts taken together shall be deemed to constitute one and the same
instrument. Delivery of this Second Amendment by facsimile transmission shall be
effective as delivery of a manually executed counterpart hereof.

5.4 No Oral Agreement. This Second Amendment, the Credit Agreement and the other
Loan Documents executed in connection herewith and therewith represent the final
agreement between the parties and may not be contradicted by evidence of prior,
contemporaneous, or unwritten oral agreements of the parties. There are no
subsequent oral agreements between the parties.

5.5 GOVERNING LAW. THIS SECOND AMENDMENT (INCLUDING, BUT NOT LIMITED TO, THE
VALIDITY AND ENFORCEABILITY HEREOF) SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

5.6 Payment of Expenses. In accordance with Section 12.03 of the Credit
Agreement, the Borrower agrees to pay or reimburse the Administrative Agent for
all of its reasonable out-of-pocket costs and reasonable expenses incurred in
connection with this Second Amendment, any other documents prepared in
connection herewith and the transactions contemplated hereby, including, without
limitation, the reasonable fees and disbursements of counsel to the
Administrative Agent.

5.7 Severability. Any provision of this Second Amendment which is prohibited or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the extent of such prohibition or unenforceability without invalidating the
remaining provisions hereof, and any such prohibition or unenforceability in any
jurisdiction shall not invalidate or render unenforceable such provision in any
other jurisdiction.

5.8 Successors and Assigns. This Agreement shall be binding upon and inure to
the benefit of the parties hereto and their respective successors and assigns.

[SIGNATURES BEGIN NEXT PAGE]

 

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IN WITNESS WHEREOF, the parties hereto have caused this Second Amendment to be
duly executed as of the date first written above.

 

BORROWER:     BILL BARRETT CORPORATION       By:   /s/ Robert W. Howard        
Robert W. Howard         Chief Financial Officer GUARANTORS:    

BILL BARRETT PRODUCTION

COMPANY

      By:   /s/ Robert W. Howard         Robert W. Howard         Chief
Financial Officer     BILL BARRETT PROPERTIES INC.       By:   /s/ Robert W.
Howard         Robert W. Howard         Chief Financial Officer     CIRCLE B
LAND COMPANY LLC       By:   /s/ Fredrick J. Barrett         Fredrick J. Barrett
        Manager     BILL BARRETT CBM CORPORATION       By:   /s/ Robert W.
Howard         Robert W. Howard         Chief Financial Officer

 

SIGNATURE PAGE TO SECOND AMENDMENT

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BILL BARRETT CBM, LLC

By: Bill Barrett CBM Corporation, as

manager

      By:   /s/ Robert W. Howard         Robert W. Howard         Chief
Financial Officer

SIGNATURE PAGE TO SECOND AMENDMENT

 

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ADMINISTRATIVE AGENT:     JPMORGAN CHASE BANK, N.A.       By:   /s/ J. Scott
Fowler         J. Scott Fowler         Senior Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     JPMORGAN CHASE BANK, N.A.       By:   /s/ J. Scott Fowler         J.
Scott Fowler         Senior Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:    

DEUTSCHE BANK TRUST COMPANY

AMERICAS

      By:   /s/ Dusan Lazarov       Name:   Dusan Lazarov       Title:   Vice
President       By:   /s/ Erin Morrissey       Name:   Erin Morrissey      
Title:   Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     BANK OF AMERICA, N.A.       By:   /s/ Stephen J. Hoffman       Name:
  Stephen J. Hoffman       Title:   Managing Director

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:    

BMO CAPITAL MARKETS FINANCING,

INC. f/k/a Harris Nesbitt Financing, Inc.

      By:   /s/ Mary Lou Allen       Name:   Mary Lou Allen       Title:   Vice
President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     U.S. BANK NATIONAL ASSOCIATION       By:   /s/ Daria Mahoney      
Name:   Daria Mahoney       Title:   Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     FORTIS CAPITAL CORP.       By:   /s/ David Montgomery       Name:  
David Montgomery       Title:   Director       By:   /s/ Ilene Fowler      
Name:   Ilene Fowler       Title:   Director

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     SUNTRUST BANK       By:   /s/ James Warren       Name:   James
Warren       Title:   Managing Director

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     UNION BANK OF CALIFORNIA, N.A.       By:   /s/ Alison Fuqua      
Name:   Alison Fuqua       Title:   Assistant Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     COMERICA BANK       By:   /s/ Rebecca L. Wilson       Name:  
Rebecca L. Wilson       Title:   Assistant Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     COMPASS BANK       By:   /s/ Murray E. Brasseux       Name:   Murray
E. Brasseux       Title:   Executive Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:    

GOLDMAN SACHS CREDIT PARTNERS

L.P.

      By:   /s/ Jaime Weisfelner       Name:   Jaime Weisfelner       Title:  
Authorized Signatory

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:    

MERRILL LYNCH CAPITAL, a division

of Merrill Lynch Business Financial

Services Inc.

      By:   /s/ Randall F. Hornick       Name:   Randall F. Hornick       Title:
  Authorized Signatory

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     CREDIT SUISSE       By:   /s/ Vanessa Gomez       Name:   Vanessa
Gomez       Title:   Director       By:   /s/ Morenikeji Ajayi       Name:  
Morenikeji Ajayi       Title:   Associate

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     WELLS FARGO BANK, N.A.       By:   /s/ Oleo Logan       Name:   Oleo
Logan       Title:   Assistant Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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LENDER:     BANK OF SCOTLAND plc       By:   /s/ Karen Weich       Name:   Karen
Weich       Title:   Vice President

SIGNATURE PAGE TO SECOND AMENDMENT

 

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