Exhibit
      10(aa)


    REGISTRATION
      RIGHTS
      AGREEMENT 

    by
      and among


    ATLAS
      ENERGY RESOURCES, LLC


    and


    THE
      PURCHASERS NAMED HEREIN


    

    
    

    TABLE
      OF CONTENTS


     

    
      	
            	
            	
            	
            	
            
	 	 	 	  	Page
	Article
              I DEFINITIONS	  	1
	
            	
            	
            
	
              Section 1.01

            	 	Definitions.	  	1
	
              Section 1.02

            	 	Registrable
              Securities.	  	3
	
            	
            
	Article
              II REGISTRATION RIGHTS	  	3
	
            	
            	
            
	
              Section 2.01

            	 	Registration.	  	5
	
              Section 2.02

            	 	Piggyback
              Rights.	  	5
	
              Section 2.03

            	 	Underwritten
              Offering.	  	7
	
              Section 2.04

            	 	Sale
              Procedures.	  	8
	
              Section 2.05

            	 	Cooperation
              by Holders.	  	12
	
              Section 2.06

            	 	Restrictions
              on Public Sale by Holders of Registrable
              Securities.	  	12
	
              Section 2.07

            	 	Expenses.	  	12
	
              Section 2.08

            	 	Indemnification.	  	13
	
              Section 2.09

            	 	Rule
              144 Reporting.	  	15
	
              Section 2.10

            	 	Transfer
              or Assignment of Registration Rights.	  	15
	
              Section 2.11

            	 	Limitation
              on Subsequent Registration Rights.	  	16
	
            	
            
	Article
              III MISCELLANEOUS	  	16
	
            	
            	
            
	
              Section 3.01

            	 	Communications.	  	16
	
              Section 3.02

            	 	Successor
              and Assigns.	  	16
	
              Section 3.03

            	 	Aggregation
              of Purchased Class D Units and Purchased
              Units.	  	16
	
              Section 3.04

            	 	Recapitalization,
              Exchanges, Etc. Affecting the Units.	  	16
	
              Section 3.05

            	 	Change
              of Control	  	17
	
              Section 3.06

            	 	Specific
              Performance.	  	17
	
              Section 3.07

            	 	Counterparts.	  	17
	
              Section 3.08

            	 	Headings.	  	17
	
              Section 3.09

            	 	Governing
              Law.	  	17
	
              Section 3.10

            	 	Severability
              of Provisions.	  	17
	
              Section 3.11

            	 	Entire
              Agreement.	  	17
	
              Section 3.12

            	 	Amendment.	  	17
	
              Section 3.13

            	 	No
              Presumption.	  	18
	
              Section 3.14

            	 	Obligations
              Limited to Parties to Agreement.	  	18


    

    

    
    

    REGISTRATION
      RIGHTS
      AGREEMENT 

    THIS
      REGISTRATION RIGHTS AGREEMENT
      (this “Agreement”) is made and entered into as of June 29, 2007 by
      and among Atlas Energy Resources, LLC, a Delaware limited liability company
      (“Atlas Energy”), and each of the Purchasers set forth in Exhibit A
(each, a “Purchaser” and, collectively, the “Purchasers”).


    WHEREAS,
      this Agreement is made in
      connection with the Closing of the issuance and sale of the Purchased Class
      D
      Units and the Purchased Units pursuant to the Class D Unit and Common Unit
      Purchase Agreement, dated as of May 18, 2007, by and among Atlas Energy and
      the Purchasers (the “Purchase Agreement”); 

    WHEREAS,
      Atlas Energy has agreed to
      provide the registration and other rights set forth in this Agreement for the
      benefit of the Purchasers pursuant to the Purchase Agreement; and 

    WHEREAS,
      it is a condition to the
      obligations of each Purchaser and Atlas Energy under the Purchase Agreement
      that
      this Agreement be executed and delivered. 

    NOW
      THEREFORE, in consideration of
      the mutual covenants and agreements set forth herein and for good and valuable
      consideration, the receipt and sufficiency of which are hereby acknowledged
      by
      each party hereto, the parties hereby agree as follows: 

    ARTICLE
      I


    DEFINITIONS
      

    Section 1.01
      Definitions. Capitalized terms used herein without definition shall
      have the meanings given to them in the Purchase Agreement. The terms set
      forth below are used herein as so defined: 

    “Agreement”
has
      the meaning
      specified therefor in the introductory paragraph. 

    “Atlas
      Energy” has the
      meaning specified therefor in the introductory paragraph. 

    “Effectiveness
      Period” has
      the meaning specified therefor in Section 2.01(a)(i) of this Agreement.


    “File
      Date” has the meaning
      specified therefor in Section 2.01(a)(i) of this Agreement. 

    “Holder”
means
      the record
      holder of any Registrable Securities. 

    “Included
      Registrable
      Securities” has the meaning specified therefor in Section 2.02(a) of
      this Agreement. 

    “Liquidated
      Damages” has the
      meaning specified therefor in Section 2.01(a)(ii) of this Agreement.


    

    
    

    “Liquidated
      Damages
      Multiplier” means the product of $25.00 times the number of Class D Units
      and Purchased Units purchased by such Purchaser. 

    “Losses”
has
      the meaning
      specified therefor in Section 2.08 of this Agreement. 

    “Managing
      Underwriter” means,
      with respect to any Underwritten Offering, the book-running lead manager of
      such
      Underwritten Offering. 

    “Opt
      Out Notice” has the
      meaning specified therefor in Section 2.02(a) of this Agreement.


    “Purchase
      Agreement” has the
      meaning specified therefor in the recitals of this Agreement. 

    “Purchaser”
and
      “Purchasers” have the meanings specified therefor in the introductory
      paragraph of this Agreement. 

    “Purchaser
      Underwriter
      Registration Statement” has the meaning specified therefor in
      Section 2.04(n) of this Agreement. 

    “Registrable
      Securities”
means: (i) the Purchased Units, (ii) Purchased Class D Units,
      (iii) the Common Units issuable upon conversion of the Purchased Class D
      Units, (iii) any Common Units or Class D Units issued as Liquidated Damages
      pursuant to this Agreement, (iv) any Common Units issuable upon conversion
      of Class D Units issued as Liquidated Damages pursuant to this Agreement,
      (v) any Common Units or Class D Units issuable pursuant to
      Section 5.02 of the Purchase Agreement, and (vi) any Common Units
      issuable upon conversion of Class D Units issuable pursuant to Section 5.02
      of the Purchase Agreement, all of which Registrable Securities are subject
      to
      the rights provided herein until such rights terminate pursuant to the
      provisions hereof. 

    “Registration
      Expenses” has
      the meaning specified therefor in Section 2.07(a) of this Agreement.


    “Registration
      Statement” has
      the meaning specified therefor in Section 2.01(a)(i) of this Agreement.


    “Selling
      Expenses” has the
      meaning specified therefor in Section 2.07(a) of this Agreement.


    “Selling
      Holder” means a
      Holder who is selling Registrable Securities pursuant to a registration
      statement. 

    “Target
      Effective Date” has
      the meaning specified therefor in Section 2.01(a)(i) of this Agreement.


    “Underwritten
      Offering” means
      an offering (including an offering pursuant to a Registration Statement) in
      which Units are sold to an underwriter on a firm commitment basis 

     

    2


    

    
    

    for
      reoffering to the public or an
      offering that is a “bought deal” with one or more investment banks.


    Section 1.02
Registrable
      Securities. Any Registrable Security will cease to be a Registrable
      Security when: (a) a registration statement covering such Registrable
      Security is effective and such Registrable Security has been sold or disposed
      of
      pursuant to such effective registration statement; (b) such Registrable
      Security has been disposed of pursuant to any section of Rule 144 (or any
      similar provision then in force) under the Securities Act; (c) two years
      after the Closing Date; (d) such Registrable Security is held by Atlas
      Energy or one of its Subsidiaries; or (e) such Registrable Security has
      been sold in a private transaction in which the transferor’s rights under this
      Agreement are not assigned to the transferee of such securities. 

    ARTICLE
      II


    REGISTRATION
      RIGHTS


    Section 2.01
      Registration. 

    (a)
Registration.
      

    (i)
Deadline
      To File and Go
      Effective. As soon as practicable following January 1, 2008, but
      in any event prior to January 31, 2008 (the “File Date”), Atlas
      Energy shall prepare and file a registration statement under the Securities
      Act
      to permit the resale of the Registrable Securities from time to time, including
      as permitted by Rule 415 under the Securities Act (or any similar provision
      then
      in force), with respect to all of the Registrable Securities (the
“Registration Statement”). Atlas Energy shall use its commercially
      reasonable efforts to cause the Registration Statement to become effective
      no
      later than May 30, 2008 (the “Target Effective Date”). A
      Registration Statement filed pursuant to this Section 2.01 shall be on Form
      S-3 under the Securities Act. Atlas Energy will use its commercially
      reasonable efforts to cause the Registration Statement filed pursuant to this
      Section 2.01 to be continuously effective under the Securities Act until
      the earlier of (i) the date as of which all such Registrable Securities are
      sold by the Purchasers and (ii) two years following the Closing Date (the
“Effectiveness Period”). The Registration Statement when effective
      (including the documents incorporated therein by reference) shall comply as
      to
      form with all applicable requirements of the Securities Act and the Exchange
      Act
      and shall not contain an untrue statement of a material fact or omit to state
      a
      material fact required to be stated therein or necessary to make the statements
      therein not misleading. 

    (ii)
Failure
      To Go
      Effective. If the Registration Statement required by Section 2.01
      is not effective by the Target Effective Date, then each Purchaser shall be
      entitled to a payment with respect to such Purchaser’s Registrable Securities,
      as liquidated damages and not as a penalty, of 0.25% of the Liquidated Damages
      Multiplier per 30-day period for the first 30 days following the Target
      Effective Date, increasing by an additional 0.25% of the Liquidated Damages
      Multiplier per 30-day period for each subsequent 30 days, up to a maximum of
      1.00% of the Liquidated Damages Multiplier per 30-day period (the “Liquidated
      Damages”). The Liquidated Damages payable pursuant to the immediately
      preceding sentence shall be payable within ten Business Days of the end of
      each
      such 30-day period. Liquidated Damages for any period of less than 30-days
      shall be prorated by multiplying Liquidated Damages to be paid in a full 30-day
      period by a fraction, the numerator of which is the number of days for which
      

     

    3


    

    
    

    Liquidated
      Damages are owed, and the
      denominator of which is 30. Any Liquidated Damages shall be paid to each
      Purchaser in cash or immediately available funds; provided,
however, if Atlas Energy certifies that it is unable to pay Liquidated
      Damages in cash or immediately available funds because such payment would result
      in a breach under any of Atlas Energy’s or Atlas Energy’s Subsidiaries’ credit
      facilities or other indebtedness filed as exhibits to the Atlas Energy SEC
      Documents, then Atlas Energy may pay the Liquidated Damages in kind in the
      form
      of the issuance of additional (A) Common Units or (B) Common Units or
      Class D Units. Class D Units may only be issued as Liquidated Damages if
      and to the extent Atlas Energy is restricted from issuing Common Units pursuant
      to the rules of The New York Stock Exchange or similar regulation. If Class
      D Units are issued as Liquidated Damages as a result of a requirement by The
      New
      York Stock Exchange or similar regulation, then such Common Units and/or Class
      D
      Units will be issued to each Purchaser on a pro rata basis in such a manner
      as
      to maximize the number of Common Units issued to each such Purchaser. Upon
      any issuance of Common Units and/or Class D Units as Liquidated Damages, Atlas
      Energy shall promptly prepare and file an amendment to the Registration
      Statement prior to its effectiveness adding such Common Units and/or Common
      Units issuable upon conversion of Class D Units to such Registration Statement
      as additional Registrable Securities. The determination of the number of
      Common Units and Class D Units to be issued as Liquidated Damages shall be
      equal
      to the amount of Liquidated Damages divided by the volume weighted average
      closing price of the Common Units (as reported by The New York Stock Exchange)
      for the ten trading days immediately preceding the date on which the Liquidated
      Damages payment is due, less a discount of 2%. Any obligation of Atlas
      Energy to pay Liquidated Damages (other than Liquidated Damages owing but not
      yet paid) to a Purchaser shall cease two years following the Closing
      Date. As soon as practicable following the date that the Registration
      Statement or any post-effective amendment thereto becomes effective, but in
      any
      event within two Business Days of such date, Atlas Energy shall provide the
      Purchasers with written notice of the effectiveness of the Registration
      Statement. 

    (iii)
Waiver
      of Liquidated
      Damages. If Atlas Energy is unable to cause a Registration Statement to
      become effective by the Target Effective Date as a result of an acquisition,
      merger, reorganization, disposition or other similar transaction, then Atlas
      Energy may request a waiver of the Liquidated Damages, which may be granted
      or
      withheld by the consent of the Holders of two-thirds of the aggregate of the
      Purchased Class D Units and the Purchased Units, voting as a single class,
      in
      their sole discretion.

    (b)
Delay
      Rights. Notwithstanding anything to the contrary contained herein,
      Atlas Energy may, upon written notice to all of the Selling Holders whose
      Registrable Securities are included in the Registration Statement, suspend
      such
      Selling Holders’ use of any prospectus which is a part of the Registration
      Statement (in which event each such Selling Holder shall discontinue sales
      of
      the Registrable Securities pursuant to the Registration Statement) but such
      Selling Holder may settle any sales of Registrable Securities, if (i) Atlas
      Energy is pursuing an acquisition, merger, reorganization, disposition or other
      similar transaction and Atlas Energy determines in good faith that Atlas
      Energy’s ability to pursue or consummate such a transaction would be materially
      adversely affected by any required disclosure of such transaction in the
      Registration Statement or (ii) Atlas Energy has experienced some other
      material non-public event, the disclosure of which at such time, in the good
      faith judgment of Atlas Energy, would materially adversely affect Atlas Energy;
      provided, however, in no event shall such Selling Holders be
      suspended from selling Registrable 

     

    4


    

    
    

    Securities
      pursuant to the
      Registration Statement for a period that exceeds an aggregate of 30 days in
      any
      90-day period or 90 days in any 365-day period. Upon disclosure of such
      information or the termination of the condition described above, Atlas Energy
      shall (i) provide prompt notice to the Selling Holders whose Registrable
      Securities are included in the Registration Statement, (ii) promptly
      terminate any suspension of sales it has put into effect and (iii) take
      such other actions to permit sales of Registrable Securities as contemplated
      in
      this Agreement. 

    (c)
Additional
      Rights to
      Liquidated Damages. If (i) the Holders shall be prohibited from
      selling their Registrable Securities under the Registration Statement as a
      result of a suspension pursuant to Section 2.01(b) of this Agreement in
      excess of the periods permitted therein or (ii) the Registration Statement
      is filed and effective but, during the Effectiveness Period, shall thereafter
      cease to be effective or fail to be usable for its intended purpose without
      being succeeded by a post-effective amendment to the Registration Statement,
      a
      supplement to the prospectus or a report filed with the Commission pursuant
      to
      Section 13(a), 13(c), 14 or l5(d) of the Exchange Act, then, until the
      suspension is lifted or a post-effective amendment, supplement or report is
      filed with the Commission and effective, but not including any day on which
      a
      suspension is lifted or such amendment, supplement or report is filed and
      effective, if applicable, Atlas Energy shall owe the Holders an amount equal
      to
      the Liquidated Damages, following (x) the date on which the suspension
      period exceeded the permitted period under Section 2.01(b) of this
      Agreement or (y) the date after the Registration Statement ceased to be
      effective or failed to be useable for its intended purposes, as liquidated
      damages and not as a penalty. For purposes of this Section 2.01(c), a
      suspension shall be deemed lifted on the date that notice that the suspension
      has been lifted or that a post-effective amendment is effective is delivered
      to
      the Holders pursuant to Section 3.01 of this Agreement. 

    (d)
S-1
      Filing. In addition
      to the rights provided in Section 2.01(a), if Atlas Energy is not eligible
      to file a shelf registration statement on Form S-3 on the File Date, one or
      more
      Holders collectively holding greater than $25 million of Registrable Securities,
      based on the Average Purchase Price, may thereafter deliver written notice
      to
      Atlas Energy that such Holders wish to register under the Securities Act an
      aggregate of at least $25 million of Registrable Securities, based on the
      Average Purchase Price specifying the amount and intended method of disposition
      of such Registrable Securities. Atlas Energy will promptly give written notice
      of such requested registration to all other Holders, and thereupon will, as
      expeditiously as possible, use its reasonable best efforts to effect the
      registration under the Securities Act of (i) such Registrable Securities
      which the Company has been so requested to register by the such Holders; and
      (ii) all other Registrable Securities which Atlas Energy has been requested
      to register by any other Holder (which request shall specify the amount and
      intended method of disposition of such Registrable Securities, including an
      Underwritten Offering) to the extent necessary to permit the disposition (in
      accordance with the intended method thereof as aforesaid) of the Registrable
      Securities so to be registered. 

    Section 2.02
Piggyback
      Rights. 

    (a)
Participation. If
      at
      any time Atlas Energy proposes to file (i) a shelf registration statement
      other than the Registration Statement (in which event Atlas Energy covenants
      and
      agrees to include thereon a description of the transaction under which the
      

     

    5


    

    
    

    Purchasers
      acquired the Registrable
      Securities) and a prospectus supplement related to such shelf
      registration, (ii) a prospectus supplement to an effective shelf
      registration statement, other than the Registration Statement contemplated
      by
      Section 2.01 of this Agreement and Holders may be included without the
      filing of a post-effective amendment thereto, or (iii) a registration
      statement, other than a shelf registration statement, in any case, for
      the sale of Common Units in an Underwritten Offering for its own account and/or
      another Person, then as soon as practicable but not less than three Business
      Days prior to the filing of (x) any preliminary prospectus supplement
      relating to such Underwritten Offering pursuant to Rule 424(b) under the
      Securities Act, (y) the prospectus supplement relating to such Underwritten
      Offering pursuant to Rule 424(b) under the Securities Act (if no preliminary
      prospectus supplement is used) or (z) such registration statement (only
      in respect of clause (iii) above for purposes of this clause (z)), as
      the case may be, then Atlas Energy shall give notice (including, but not limited
      to, notification by electronic mail) of such proposed Underwritten Offering
      to
      the Holders and such notice shall offer the Holders the opportunity to include
      in such Underwritten Offering such number of Common Units (the “Included
      Registrable Securities”) as each such Holder may request in writing;
provided, however, that if Atlas Energy has been advised by the
      Managing Underwriter that the inclusion of Registrable Securities for sale
      for
      the benefit of the Holders will have a material adverse effect on the price,
      timing or distribution of the Common Units in the Underwritten Offering, then
      the amount of Registrable Securities to be offered for the accounts of Holders
      shall be determined based on the provisions of Section 2.02(b) of this
      Agreement. The notice required to be provided in this Section 2.02(a)
      to Holders shall be provided on a Business Day pursuant to Section 3.01
      hereof and receipt of such notice shall be confirmed by such Holder. Each
      such Holder shall then have three Business Days after receiving such notice
      to
      request inclusion of Registrable Securities in the Underwritten
      Offering. If no request for inclusion from a Holder is received within the
      specified time, such Holder shall have no further right to participate in such
      Underwritten Offering. If, at any time after giving written notice of its
      intention to undertake an Underwritten Offering and prior to the closing of
      such
      Underwritten Offering, Atlas Energy shall determine for any reason not to
      undertake or to delay such Underwritten Offering, Atlas Energy may, at its
      election, give written notice of such determination to the Selling Holders
      and,
      (x) in the case of a determination not to undertake such Underwritten
      Offering, shall be relieved of its obligation to sell any Included Registrable
      Securities in connection with such terminated Underwritten Offering, and
      (y) in the case of a determination to delay such Underwritten Offering,
      shall be permitted to delay offering any Included Registrable Securities for
      the
      same period as the delay in the Underwritten Offering. Any Selling Holder
      shall have the right to withdraw such Selling Holder’s request for inclusion of
      such Selling Holder’s Registrable Securities in such offering by giving written
      notice to Atlas Energy of such withdrawal up to and including the time of
      pricing of such offering. Each Holder’s rights under this
      Section 2.02(a) shall terminate when such Holder (together with any
      Affiliates of such Holder) holds less than $15 million, in aggregate, of
      Registrable Securities, based on the Average Purchase
      Price. Notwithstanding the foregoing, any Holder may deliver written notice
      (an “Opt Out Notice”) to Atlas Energy requesting that such Holder not
      receive notice from Atlas Energy of any proposed Underwritten Offering;
provided, that such Holder may later revoke any such notice.


    (b)
Priority
      of
      Rights. If the Managing Underwriter or Underwriters of any proposed
      Underwritten Offering of Common Units included in an Underwritten Offering
      involving Included Registrable Securities advises Atlas Energy, or Atlas Energy
      reasonably determines, that the total amount of Registrable Securities that
      the
      Selling Holders and any other Persons intend to include 

     

    6


    

    
    

    in
      such offering exceeds the number
      that can be sold in such offering without being likely to have a material
      adverse effect on the price, timing or distribution of the Common Units offered
      or the market for the Common Units, then the Registrable Securities to be
      included in such Underwritten Offering shall include the number of Registrable
      Securities that such Managing Underwriter or Underwriters advises Atlas Energy,
      or Atlas Energy reasonably determines, can be sold without having such adverse
      effect, with such number to be allocated (i) first, to Atlas Energy, and
      (ii) second, pro rata among the Selling Holders who have requested
      participation in such Underwritten Offering. The pro rata allocations for
      each such Selling Holder shall be the product of (a) the aggregate number
      of Registrable Securities proposed to be sold by all Selling Holders in such
      Underwritten Offering multiplied by (b) the fraction derived by dividing
      (x) the number of Registrable Securities owned on the Closing Date by such
      Selling Holder by (y) the aggregate number of Registrable Securities owned
      on the Closing Date by all Selling Holders participating in the Underwritten
      Offering. All participating Selling Holders shall have the opportunity to
      share pro rata that portion of such priority allocable to any Selling Holder(s)
      not so participating. 

    Section 2.03
Underwritten
      Offering. 

    (a)
Request
      for Underwritten
      Offering. In the event that one or more Holders collectively holding greater
      than $75 million of Registrable Securities, based on the Average Purchase Price,
      elect to dispose of Registrable Securities under the Registration Statement
      (including a registration statement pursuant to Section 2.01(d)) pursuant
      to an Underwritten Offering, Atlas Energy shall retain underwriters, effect
      such
      sale though an Underwritten Offering, including entering into an underwriting
      agreement in customary form with the Managing Underwriter or Underwriters,
      which
      shall include, among other provisions, indemnities to the effect and to the
      extent provided in Section 2.08 and take all reasonable actions as are
      requested by the Managing Underwriter or Underwriters to expedite or facilitate
      the disposition of such Registrable Securities. Atlas Energy management shall
      participate in a roadshow or similar marketing effort on behalf of any such
      Holder or Holders if gross proceeds from such Underwritten Offering are
      reasonably expected to exceed $75 million. 

    (b)
Limitation
      on Underwritten
      Offerings. In connection with any and all rights granted hereunder to the
      Holders to cause Atlas Energy to engage underwriters to conduct an Underwritten
      Offering on behalf of the Holders, in no event shall Atlas Energy be required
      to
      do more than aggregate of four such Underwritten Offerings. 

    (c)
General
      Procedures. In connection with any Underwritten Offering under this
      Agreement, Atlas Energy shall be entitled to select the Managing Underwriter
      or
      Underwriters. In connection with an Underwritten Offering contemplated by
      this Agreement in which a Selling Holder participates, each Selling Holder
      and
      Atlas Energy shall be obligated to enter into an underwriting agreement that
      contains such representations, covenants, indemnities and other rights and
      obligations as are customary in underwriting agreements for firm commitment
      offerings of securities. No Selling Holder may participate in such
      Underwritten Offering unless such Selling Holder agrees to sell its Registrable
      Securities on the basis provided in such underwriting agreement and completes
      and executes all questionnaires, powers of attorney, indemnities and other
      documents reasonably required under the terms of such 

     

    7


    

    
    

    underwriting
      agreement. Each
      Selling Holder may, at its option, require that any or all of the
      representations and warranties by, and the other agreements on the part of,
      Atlas Energy to and for the benefit of such underwriters also be made to and
      for
      such Selling Holder’s benefit and that any or all of the conditions precedent to
      the obligations of such underwriters under such underwriting agreement also
      be
      conditions precedent to its obligations. No Selling Holder shall be
      required to make any representations or warranties to or agreements with Atlas
      Energy or the underwriters other than representations, warranties or agreements
      regarding such Selling Holder and its ownership of the securities being
      registered on its behalf, its intended method of distribution and any other
      representation required by Law. If any Selling Holder disapproves of the
      terms of an underwriting, such Selling Holder may elect to withdraw therefrom
      by
      notice to Atlas Energy and the Managing Underwriter; provided,
however, that such withdrawal must be made at a time up to and including
      the time of pricing of such Underwritten Offering. No such withdrawal or
      abandonment shall affect Atlas Energy’s obligation to pay Registration Expenses.


    Section 2.04
Sale
      Procedures. In connection with its obligations under this Article II,
      Atlas Energy will, as expeditiously as possible: 

    (a)
      prepare and file with the
      Commission such amendments and supplements to the Registration Statement and
      the
      prospectus used in connection therewith as may be necessary to cause the
      Registration Statement to be effective and to keep the Registration Statement
      effective for the Effectiveness Period and as may be necessary to comply with
      the provisions of the Securities Act with respect to the disposition of all
      securities covered by the Registration Statement; 

    (b)
      furnish to each Selling Holder
      (i) as far in advance as reasonably practicable before filing the
      Registration Statement or any other registration statement contemplated by
      this
      Agreement or any supplement or amendment thereto, upon request, copies of
      reasonably complete drafts of all such documents proposed to be filed (including
      exhibits and each document incorporated by reference therein to the extent
      then
      required by the rules and regulations of the Commission), and provide each
      such
      Selling Holder the opportunity to object to any information pertaining to such
      Selling Holder and its plan of distribution that is contained therein and make
      the corrections reasonably requested by such Selling Holder with respect to
      such
      information prior to filing the Registration Statement or such other
      registration statement or supplement or amendment thereto, and (ii) such
      number of copies of the Registration Statement or such other registration
      statement and the prospectus included therein and any supplements and amendments
      thereto as such Persons may reasonably request in order to facilitate the public
      sale or other disposition of the Registrable Securities covered by such
      Registration Statement or other registration statement; 

    (c)
      if applicable, use its
      commercially reasonable efforts to register or qualify the Registrable
      Securities covered by the Registration Statement or any other registration
      statement contemplated by this Agreement under the securities or blue sky laws
      of such jurisdictions as the Selling Holders or, in the case of an Underwritten
      Offering, the Managing Underwriter, shall reasonably request; provided,
however, that Atlas Energy will not be required to qualify generally
      to
      transact business in any jurisdiction where it is not then required to so
      qualify or to take any action which would subject it to general service of
      process in any such jurisdiction where it is not then so subject; 

     

    8


    

    
    

    (d)
      promptly notify each Selling
      Holder and each underwriter of Registrable Securities, at any time when a
      prospectus relating thereto is required to be delivered by any of them under
      the
      Securities Act, of (i) the filing of the Registration Statement or any
      other registration statement contemplated by this Agreement or any prospectus
      to
      be used in connection therewith, or any amendment or supplement thereto, and,
      with respect to such Registration Statement or any other registration statement
      or any post-effective amendment thereto, when the same has become effective;
      and
      (ii) any written comments from the Commission with respect to any filing
      referred to in clause (i) and any written request by the Commission for
      amendments or supplements to the Registration Statement or any other
      registration statement or any prospectus or prospectus supplement thereto;
      

    (e)
      immediately notify each Selling
      Holder and each underwriter of Registrable Securities, at any time when a
      prospectus relating thereto is required to be delivered under the Securities
      Act, of (i) the happening of any event as a result of which the prospectus
      or prospectus supplement contained in the Registration Statement or any other
      registration statement contemplated by this Agreement, as then in effect,
      includes an untrue statement of a material fact or omits to state any material
      fact required to be stated therein or necessary to make the statements therein
      not misleading in the light of the circumstances then existing; (ii) the
      issuance or threat of issuance by the Commission of any stop order suspending
      the effectiveness of the Registration Statement or any other registration
      statement contemplated by this Agreement, or the initiation of any proceedings
      for that purpose; or (iii) the receipt by Atlas Energy of any notification
      with respect to the suspension of the qualification of any Registrable
      Securities for sale under the applicable securities or blue sky laws of any
      jurisdiction. Following the provision of such notice, Atlas Energy agrees
      to as promptly as practicable amend or supplement the prospectus or prospectus
      supplement or take other appropriate action so that the prospectus or prospectus
      supplement does not include an untrue statement of a material fact or omit
      to
      state a material fact required to be stated therein or necessary to make the
      statements therein not misleading in the light of the circumstances then
      existing and to take such other action as is necessary to remove a stop order,
      suspension, threat thereof or proceedings related thereto; 

    (f)
      upon request and subject to
      appropriate confidentiality obligations, furnish to each Selling Holder copies
      of any and all transmittal letters or other correspondence with the Commission
      or any other governmental agency or self-regulatory body or other body having
      jurisdiction (including any domestic or foreign securities exchange) relating
      to
      such offering of Registrable Securities; 

    (g)
      in the case of an Underwritten
      Offering, furnish upon request, (i) an opinion of counsel for Atlas Energy
      dated the effective date of the applicable registration statement or the date
      of
      any amendment or supplement thereto, and a letter of like kind dated the date
      of
      the closing under the underwriting agreement, and (ii) a “cold comfort”
letter, dated the date of the applicable registration statement or the date
      of
      any amendment or supplement thereto and a letter of like kind dated the date
      of
      the closing under the underwriting agreement, in each case, signed by the
      independent public accountants who have certified Atlas Energy’s financial
      statements included or incorporated by reference into the applicable
      registration statement, and each of the opinion and the “cold comfort” letter
      shall be in customary form and covering substantially the same matters with
      respect to such registration statement (and the prospectus and any prospectus
      supplement included therein) as are customarily covered in opinions of issuer’s
      counsel and in 

     

    9


    

    
    

    accountants’
letters
      delivered to
      the underwriters in Underwritten Offerings of securities and such other matters
      as such underwriters or Selling Holders may reasonably request; 

    (h)
      otherwise use its commercially
      reasonable efforts to comply with all applicable rules and regulations of the
      Commission, and make available to its security holders, as soon as reasonably
      practicable, an earnings statement, which earnings statement shall satisfy
      the
      provisions of Section 11(a) of the Securities Act and Rule 158 promulgated
      thereunder; 

    (i)
      make available to the
      appropriate representatives of the Managing Underwriter and Selling Holders
      access to such information and Atlas Energy personnel as is reasonable and
      customary to enable such parties to establish a due diligence defense under
      the
      Securities Act; provided, however, that Atlas Energy need not
      disclose any such information to any such representative unless and until such
      representative has entered into or is otherwise subject to a confidentiality
      agreement with Atlas Energy satisfactory to Atlas Energy (including any
      confidentiality agreement referenced in Section 8.06 of the Purchase
      Agreement); 

    (j)
      cause all such Registrable
      Securities registered pursuant to this Agreement to be listed on each securities
      exchange or nationally recognized quotation system on which similar securities
      issued by Atlas Energy are then listed; 

    (k)
      use its commercially reasonable
      efforts to cause the Registrable Securities to be registered with or approved
      by
      such other governmental agencies or authorities as may be necessary by virtue
      of
      the business and operations of Atlas Energy to enable the Selling Holders to
      consummate the disposition of such Registrable Securities; 

    (l)
      provide a transfer agent and
      registrar for all Registrable Securities covered by such registration statement
      not later than the effective date of such registration statement; 

    (m)
      enter into customary agreements
      and take such other actions as are reasonably requested by the Selling Holders
      or the underwriters, if any, in order to expedite or facilitate the disposition
      of such Registrable Securities; 

    (n)
      If any Purchaser could
      reasonably be deemed to be an “underwriter,” as defined in Section 2(a)(11)
      of the Securities Act, in connection with the registration statement in respect
      of any registration of Registrable Securities of such Purchaser pursuant to
      this
      Agreement, and any amendment or supplement thereof (any such registration
      statement or amendment or supplement, a “Purchaser Underwriter Registration
      Statement”), then for a period of two years following the File Date, Atlas
      Energy will cooperate with such Purchaser in allowing such Purchaser to conduct
      customary “underwriter’s due diligence” with respect to Atlas Energy and satisfy
      its obligations in respect thereof. In addition, for a period of one year
      following the File Date at any Purchaser’s request, Atlas Energy will furnish to
      such Purchaser, on the date of the effectiveness of any Purchaser Underwriter
      Registration Statement and thereafter no more often than on a quarterly basis,
      (i) a letter, dated such date, from Atlas Energy’s independent certified
      public accountants in form and substance as is customarily given by independent
      certified public accountants to underwriters in an underwritten public offering,
      addressed to such Purchaser, (ii) an opinion, dated as of such date, of
      counsel representing 

     

    10


    

    
    

    Atlas
      Energy for purposes of such
      Purchaser Underwriter Registration Statement, in form, scope and substance
      as is
      customarily given in an underwritten public offering, including a standard
      “10b-5” opinion for such offering, addressed to such Purchaser and (iii) a
      standard officer’s certificate from the Chief Executive Officer and Chief
      Financial Officer of Atlas Energy addressed to such Purchaser. Atlas Energy
      will also permit one legal counsel to such Purchaser(s) to review and comment
      upon any such Purchaser Underwriter Registration Statement at least five
      Business Days prior to its filing with the Commission and all amendments and
      supplements to any such Purchaser Underwriter Registration Statement within
      a
      reasonable number of days prior to their filing with the Commission and not
      file
      any Purchaser Underwriter Registration Statement or amendment or supplement
      thereto in a form to which such Purchaser’s legal counsel reasonably objects;


    (o)
      Each Selling Holder, upon
      receipt of notice from Atlas Energy of the happening of any event of the kind
      described in Section 2.04(e) of this Agreement, shall forthwith discontinue
      disposition of the Registrable Securities until such Selling Holder’s receipt of
      the copies of the supplemented or amended prospectus contemplated by
      Section 2.04(e) of this Agreement or until it is advised in writing by
      Atlas Energy that the use of the prospectus may be resumed and has received
      copies of any additional or supplemental filings incorporated by reference
      in
      the prospectus, and, if so directed by Atlas Energy, such Selling Holder will,
      or will request the managing underwriter or underwriters, if any, to deliver
      to
      Atlas Energy (at Atlas Energy’s expense) all copies in their possession or
      control, other than permanent file copies then in such Selling Holder’s
      possession, of the prospectus covering such Registrable Securities current
      at
      the time of receipt of such notice; 

    (p)
      If requested by a Purchaser,
      Atlas Energy shall: (i) as soon as practicable incorporate in a prospectus
      supplement or post-effective amendment such information as such Purchaser
      reasonably requests to be included therein relating to the sale and distribution
      of Registrable Securities, including information with respect to the number
      of
      Registrable Securities being offered or sold, the purchase price being paid
      therefor and any other terms of the offering of the Registrable Securities
      to be
      sold in such offering; (ii) as soon as practicable make all required
      filings of such prospectus supplement or post-effective amendment after being
      notified of the matters to be incorporated in such prospectus supplement or
      post-effective amendment; and (iii) as soon as practicable, supplement or
      make amendments to any Registration Statement; and 

    (q)
      Include in the plan of
      distribution section of a registrations statement the following language with
      respect to the selling unitholders: 

    “The
      selling unitholders may enter
      into derivative transactions with third parties, or sell securities not covered
      by this prospectus to third parties in privately negotiated transactions. If
      the
      applicable prospectus supplement indicates, in connection with those
      derivatives, the third parties may sell securities covered by this prospectus
      and the applicable prospectus supplement, including in short sale transactions.
      If so, the third party may use securities 

     

    11


    

    
    

    pledged
      by the selling unitholders
      or borrowed from the selling unitholders or others to settle those sales or
      to
      close out any related open borrowings of Units, and may use securities received
      from the selling unitholders in settlement of those derivatives to close out
      any
      related open borrowings of Units.” 

    Section 2.05
Cooperation
      by
      Holders. Atlas Energy shall have no obligation to include in the
      Registration Statement Registrable Securities of a Holder, or in an Underwritten
      Offering pursuant to Section 2.02 Registrable Securities of a Selling
      Holder, who has failed to timely furnish such information that Atlas Energy
      determines, after consultation with counsel, is reasonably required to be
      furnished or conformed in order for the registration statement or prospectus
      supplement, as applicable, to comply with the Securities Act. 

    Section 2.06
Restrictions
      on
      Public Sale by Holders of Registrable Securities. For a period of 365 days
      from the Closing Date, each Holder of Registrable Securities agrees not to
      effect any public sale or distribution of the Registrable Securities for a
      period of up to 30 days following completion of an Underwritten Offering of
      equity securities by Atlas Energy (except as provided in this
      Section 2.06); provided, however, that the duration of the
      foregoing restrictions shall be no longer than the duration of the shortest
      restriction generally imposed by the underwriters on the officers or directors
      or any other Unitholder of Atlas Energy on whom a restriction is imposed in
      connection with such public offering. In addition, the provisions of this
      Section 2.06 shall not apply with respect to a Holder that (A) owns
      less than $25 million, in aggregate, of Registrable Securities based on the
      Average Purchase Price or (B) has delivered an Opt Out Notice to Atlas
      Energy pursuant to Section 2.02(a) hereof; provided, however, the
      above shall not apply, in the case of a Purchaser that is a large multi-unit
      investment or commercial banking organization, to activities in the normal
      course of trading of units of such Purchaser other than the unit participating
      in this transaction so long as such other units are not acting on behalf of
      the
      unit participating in this transaction and have not been provided with
      confidential information regarding Atlas Energy by the unit participating in
      this transaction; provided further, with respect to Goldman,
      Sachs & Co., the restrictions contained in this Section 2.06 shall
      only apply to the Goldman Sachs Principal Strategies Group, as currently
      configured, and shall not restrict or limit the activities of any area or
      division of Goldman, Sachs & Co. or any of its Affiliates, other than
      Goldman Sachs Principal Strategies Group, as currently configured. 

    Section 2.07
Expenses.
      

    (a)
Certain
      Definitions. “Registration Expenses” means all expenses incident
      to Atlas Energy’s performance under or compliance with this Agreement to effect
      the registration of Registrable Securities on the Registration Statement
      pursuant to Section 2.01 hereof or an Underwritten Offering covered under
      this Agreement, and the disposition of such securities, including, without
      limitation, all registration, filing, securities exchange listing and The New
      York Stock Exchange fees, all registration, filing, qualification and other
      fees
      and expenses of complying with securities or blue sky laws, fees of the National
      Association of Securities Dealers, Inc., transfer taxes and fees of transfer
      agents and registrars, all word processing, duplicating and printing expenses
      

     

    12


    

    
    

    and
      the fees and disbursements of
      one counsel to the Holders and independent public accountants for Atlas Energy,
      including the expenses of any special audits or “cold comfort” letters required
      by or incident to such performance and compliance. “Selling
      Expenses” means all underwriting fees, discounts and selling commissions
      allocable to the sale of the Registrable Securities. 

    (b)
Expenses. Atlas
      Energy will pay all reasonable Registration Expenses as determined in good
      faith, including, in the case of an Underwritten Offering, whether or not any
      sale is made pursuant to such Underwritten Offering. In addition, except as
      otherwise provided in Section 2.08 hereof, Atlas Energy shall not be
      responsible for legal fees incurred by Holders in connection with the exercise
      of such Holders’ rights hereunder. Each Selling Holder shall pay its pro
      rata share of all Selling Expenses in connection with any sale of its
      Registrable Securities hereunder. 

    Section 2.08
      Indemnification. 

    (a)
By
      Atlas Energy. In
      the event of an offering of any Registrable Securities under the Securities
      Act
      pursuant to this Agreement, Atlas Energy will indemnify and hold harmless each
      Selling Holder thereunder, its Affiliates that own Registrable Securities and
      their respective directors and officers, and each underwriter, pursuant to
      the
      applicable underwriting agreement with such underwriter, of Registrable
      Securities thereunder and each Person, if any, who controls such Selling Holder
      or underwriter within the meaning of the Securities Act and the Exchange Act,
      and its directors and officers (collectively, the “Selling Holder Indemnified
      Persons”), against any losses, claims, damages, expenses or liabilities
      (including reasonable attorneys’ fees and expenses) (collectively,
“Losses”), joint or several, to which such Selling Holder Indemnified
      Person may become subject under the Securities Act, the Exchange Act or
      otherwise, insofar as such Losses (or actions or proceedings, whether commenced
      or threatened, in respect thereof) arise out of or are based upon any untrue
      statement or alleged untrue statement of any material fact contained in the
      Registration Statement or any other registration statement contemplated by
      this
      Agreement, any preliminary prospectus, free writing prospectus or final
      prospectus contained therein, or any amendment or supplement thereof, arise
      out
      of or are based upon the omission or alleged omission to state therein a
      material fact required to be stated therein or necessary to make the statements
      therein (in the case of a prospectus, in light of the circumstances under which
      they were made) not misleading or arise out of or are based upon a Selling
      Holder being deemed to be an “underwriter,” as defined in Section 2(a)(11)
      of the Securities Act, in connection with the registration statement in respect
      of any registration of Atlas Energy’s securities, and will reimburse each such
      Selling Holder Indemnified Person for any legal or other expenses reasonably
      incurred by them in connection with investigating or defending any such Loss
      or
      actions or proceedings; provided, however, that Atlas Energy will
      not be liable in any such case if and to the extent that any such Loss arises
      out of or is based upon an untrue statement or alleged untrue statement or
      omission or alleged omission so made in strict conformity with information
      furnished by such Selling Holder Indemnified Person in writing specifically
      for
      use in the Registration Statement or such other registration statement, or
      prospectus supplement, as applicable. Such indemnity shall remain in full
      force and effect regardless of any investigation made by or on behalf of such
      Selling Holder or any such Selling Holder, its directors or officers or any
      underwriter or controlling Person, and shall survive the transfer of such
      securities by such Selling Holder. 

     

    13


    

    
    

    (b)
By
      Each Selling
      Holder. Each Selling Holder agrees severally and not jointly to
      indemnify and hold harmless Atlas Energy, its directors and officers, and each
      Person, if any, who controls Atlas Energy within the meaning of the Securities
      Act or of the Exchange Act, and its directors and officers, to the same extent
      as the foregoing indemnity from Atlas Energy to the Selling Holders, but only
      with respect to information regarding such Selling Holder furnished in writing
      by or on behalf of such Selling Holder expressly for inclusion in the
      Registration Statement or any preliminary prospectus or final prospectus
      included therein, or any amendment or supplement thereto; provided,
however, that the liability of each Selling Holder shall not be greater
      in amount than the dollar amount of the proceeds (net of any Selling Expenses)
      received by such Selling Holder from the sale of the Registrable Securities
      giving rise to such indemnification. 

    (c)
Notice. Promptly
      after receipt by an indemnified party hereunder of notice of the commencement
      of
      any action, such indemnified party shall, if a claim in respect thereof is
      to be
      made against the indemnifying party hereunder, notify the indemnifying party
      in
      writing thereof, but the omission so to notify the indemnifying party shall
      not
      relieve it from any liability which it may have to any indemnified party other
      than under this Section 2.08. In any action brought against any
      indemnified party, it shall notify the indemnifying party of the commencement
      thereof. The indemnifying party shall be entitled to participate in and, to
      the extent it shall wish, to assume and undertake the defense thereof with
      counsel reasonably satisfactory to such indemnified party and, after notice
      from
      the indemnifying party to such indemnified party of its election so to assume
      and undertake the defense thereof, the indemnifying party shall not be liable
      to
      such indemnified party under this Section 2.08 for any legal expenses
      subsequently incurred by such indemnified party in connection with the defense
      thereof other than reasonable costs of investigation and of liaison with counsel
      so selected; provided, however, that, (i) if the indemnifying
      party has failed to assume the defense or employ counsel reasonably acceptable
      to the indemnified party or (ii) if the defendants in any such action
      include both the indemnified party and the indemnifying party and counsel to
      the
      indemnified party shall have concluded that there may be reasonable defenses
      available to the indemnified party that are different from or additional to
      those available to the indemnifying party, or if the interests of the
      indemnified party reasonably may be deemed to conflict with the interests of
      the
      indemnifying party, then the indemnified party shall have the right to select
      a
      separate counsel and to assume such legal defense and otherwise to participate
      in the defense of such action, with the reasonable expenses and fees of such
      separate counsel and other reasonable expenses related to such participation
      to
      be reimbursed by the indemnifying party as incurred. Notwithstanding any
      other provision of this Agreement, no indemnified party shall settle any action
      brought against it with respect to which it is entitled to indemnification
      hereunder without the consent of the indemnifying party, unless the settlement
      thereof imposes no liability or obligation on, and includes a complete and
      unconditional release from all liability of, the indemnifying party.


    (d)
Contribution. If
      the
      indemnification provided for in this Section 2.08 is held by a court or
      government agency of competent jurisdiction to be unavailable to any indemnified
      party or is insufficient to hold them harmless in respect of any Losses, then
      each such indemnifying party, in lieu of indemnifying such indemnified party,
      shall contribute to the amount paid or payable by such indemnified party as
      a
      result of such Loss in such proportion as is appropriate to reflect the relative
      fault of the indemnifying party on the one hand and of such indemnified party
      on
      the other in connection with the statements or omissions which resulted in
      

     

    14


    

    
    

    such
      Losses, as well as any other
      relevant equitable considerations; provided, however, that in no
      event shall such Selling Holder be required to contribute an aggregate amount
      in
      excess of the dollar amount of proceeds (net of Selling Expenses) received
      by
      such Selling Holder from the sale of Registrable Securities giving rise to
      such
      indemnification. The relative fault of the indemnifying party on the one
      hand and the indemnified party on the other shall be determined by reference
      to,
      among other things, whether the untrue or alleged untrue statement of a material
      fact or the omission or alleged omission to state a material fact has been
      made
      by, or relates to, information supplied by such party, and the parties’ relative
      intent, knowledge, access to information and opportunity to correct or prevent
      such statement or omission. The parties hereto agree that it would not be
      just and equitable if contributions pursuant to this paragraph were to be
      determined by pro rata allocation or by any other method of allocation which
      does not take account of the equitable considerations referred to
      herein. The amount paid by an indemnified party as a result of the Losses
      referred to in the first sentence of this paragraph shall be deemed to include
      any legal and other expenses reasonably incurred by such indemnified party
      in
      connection with investigating or defending any Loss which is the subject of
      this
      paragraph. No person guilty of fraudulent misrepresentation (within the
      meaning of Section 11(f) of the Securities Act) shall be entitled to
      contribution from any Person who is not guilty of such fraudulent
      misrepresentation. 

    (e)
Other
      Indemnification. The provisions of this Section 2.08 shall be in
      addition to any other rights to indemnification or contribution which an
      indemnified party may have pursuant to law, equity, contract or otherwise.
      

    Section 2.09
Rule
      144
      Reporting. With a view to making available the benefits of certain
      rules and regulations of the Commission that may permit the sale of the
      Registrable Securities to the public without registration, Atlas Energy agrees
      to use its commercially reasonable efforts to: 

    (a)
      make and keep public information
      regarding Atlas Energy available, as those terms are understood and defined
      in
      Rule 144 under the Securities Act, at all times from and after the date hereof;
      

    (b)
      file with the Commission in a
      timely manner all reports and other documents required of Atlas Energy under
      the
      Securities Act and the Exchange Act at all times from and after the date hereof;
      and 

    (c)
      so long as a Holder owns any
      Registrable Securities, furnish, unless otherwise not available at no charge
      by
      access electronically to the Commission’s EDGAR filing system, to such Holder
      forthwith upon request a copy of the most recent annual or quarterly report
      of
      Atlas Energy, and such other reports and documents so filed as such Holder
      may
      reasonably request in availing itself of any rule or regulation of the
      Commission allowing such Holder to sell any such securities without
      registration. 

    Section 2.10
Transfer
      or
      Assignment of Registration Rights. The rights to cause Atlas Energy to
      register Registrable Securities granted to the Purchasers by Atlas Energy under
      this Article II may be transferred or assigned by any Purchaser to one or more
      transferee(s) or assignee(s) of such Registrable Securities or by total return
      swap; provided, however, that, except 

     

    15


    

    
    

    with
      respect to a total return swap,
      (a) unless such transferee is an Affiliate of such Purchaser or another
      Purchaser, each such transferee or assignee holds Registrable Securities in
      the
      amount of $10 million, based on the Average Purchase Price, (b) Atlas
      Energy is given written notice prior to any said transfer or assignment, stating
      the name and address of each such transferee and identifying the securities
      with
      respect to which such registration rights are being transferred or assigned,
      and
      (c) each such transferee assumes in writing responsibility for its portion
      of the obligations of such Purchaser under this Agreement. 

    Section 2.11
Limitation
      on
      Subsequent Registration Rights. From and after the date hereof, Atlas
      Energy shall not, without the prior written consent of the Holders of
      Registrable Securities, (i) enter into any agreement with any current or
      future holder of any securities of Atlas Energy that would allow such current
      or
      future holder to require Atlas Energy to include securities in any registration
      statement filed by Atlas Energy on a basis that is superior in any way to the
      piggyback rights granted to the Purchasers hereunder or (ii) grant
      registration rights to any other Person that would be superior to the
      Purchasers’ registration rights hereunder. 

    ARTICLE
      III


    MISCELLANEOUS
      

    Section 3.01
      Communications. All notices and other communications provided for or
      permitted hereunder shall be made in writing by facsimile, electronic mail,
      courier service or personal delivery: 

    (a)
      if to Atlas Energy, to the
      address set forth on its signature page; 

    (b)
      if to a Purchaser, to the
      address set forth on Exhibit A; and 

    (c)
      if to a transferee of Purchaser,
      to such Holder at the address provided pursuant to Section 2.10 hereof.


    All
      such notices and communications
      shall be deemed to have been received: at the time delivered by hand, if
      personally delivered; when receipt acknowledged, if sent via facsimile or
      electronic mail; and when actually received, if sent by courier service or
      any
      other means. 

    Section 3.02
Successor
      and
      Assigns. This Agreement shall inure to the benefit of and be binding
      upon the successors and assigns of each of the parties, including subsequent
      Holders of Registrable Securities to the extent permitted herein. 

    Section 3.03
Aggregation
      of
      Purchased Class D Units and Purchased Units. All Purchased Class D
      Units and Purchased Units held or acquired by Persons who are Affiliates of
      one
      another shall be aggregated together for the purpose of determining the
      availability of any rights under this Agreement. 

    Section 3.04
      Recapitalization, Exchanges, Etc. Affecting the Units. The
      provisions of this Agreement shall apply to the full extent set forth herein
      with respect to any and all units of Atlas Energy or any successor or assign
      of
      Atlas Energy (whether by merger, consolidation, sale of assets or otherwise)
      which may be issued in respect of, in exchange for or in substitution of, the
      Registrable Securities, and shall be appropriately adjusted for combinations,
      unit splits, 

     

    16


    

    
    

    recapitalizations
      and the like
      occurring after the date of this Agreement, including any issuance pursuant
      to
      Section 5.02 of the Purchase Agreement. 

    Section 3.05
Change
      of
      Control. Atlas Energy shall not merge, consolidate or combine with any other
      Person unless the agreement providing for such merger, consolidation or
      combination expressly provides for the continuation of the registration rights
      specified in this Agreement with respect to the Registrable Securities or other
      equity securities issued pursuant to such merger, consolidation or combination.
      

    Section 3.06
Specific
      Performance. Damages in the event of breach of this Agreement by a
      party hereto may be difficult, if not impossible, to ascertain, and it is
      therefore agreed that each such Person, in addition to and without limiting
      any
      other remedy or right it may have, will have the right to an injunction or
      other
      equitable relief in any court of competent jurisdiction, enjoining any such
      breach, and enforcing specifically the terms and provisions hereof, and each
      of
      the parties hereto hereby waives any and all defenses it may have on the ground
      of lack of jurisdiction or competence of the court to grant such an injunction
      or other equitable relief. The existence of this right will not preclude
      any such Person from pursuing any other rights and remedies at law or in equity
      which such Person may have. 

    Section 3.07
      Counterparts. This Agreement may be executed in any number of
      counterparts and by different parties hereto in separate counterparts, each
      of
      which counterparts, when so executed and delivered, shall be deemed to be an
      original and all of which counterparts, taken together, shall constitute but
      one
      and the same Agreement. 

    Section 3.08
      Headings. The headings in this Agreement are for convenience of
      reference only and shall not limit or otherwise affect the meaning hereof.
      

    Section 3.09
Governing
      Law. The Laws of the State of New York shall govern this Agreement
      without regard to principles of conflict of Laws. 

    Section 3.10
Severability
      of
      Provisions. Any provision of this Agreement 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 or affecting or impairing the validity or
      enforceability of such provision in any other jurisdiction. 

    Section 3.11
Entire
      Agreement. This Agreement is intended by the parties as a final
      expression of their agreement and intended to be a complete and exclusive
      statement of the agreement and understanding of the parties hereto in respect
      of
      the subject matter contained herein. There are no restrictions, promises,
      warranties or undertakings, other than those set forth or referred to herein
      with respect to the rights granted by Atlas Energy set forth herein. This
      Agreement and the Purchase Agreement supersede all prior agreements and
      understandings between the parties with respect to such subject matter.


    Section 3.12
      Amendment. This Agreement may be amended only by means of a written
      amendment signed by Atlas Energy and the Holders of a majority of the then
      outstanding Registrable Securities; provided, however, that no
      such amendment shall materially and adversely affect the rights of any Holder
      hereunder without the consent of such Holder. 

     

    17


    

    
    

    Section 3.13
No
      Presumption. If any claim is made by a party relating to any conflict,
      omission or ambiguity in this Agreement, no presumption or burden of proof
      or
      persuasion shall be implied by virtue of the fact that this Agreement was
      prepared by or at the request of a particular party or its counsel.


    Section 3.14
Obligations
      Limited to Parties to Agreement. Each of the Parties hereto covenants,
      agrees and acknowledges that no Person other than the Purchasers (and their
      permitted assignees) and Atlas Energy shall have any obligation hereunder and
      that, notwithstanding that one or more of the Purchasers may be a corporation,
      partnership or limited liability company, no recourse under this Agreement
      or
      the Purchase Agreement or under any documents or instruments delivered in
      connection herewith or therewith shall be had against any former, current or
      future director, officer, employee, agent, general or limited partner, manager,
      member, stockholder or Affiliate of any of the Purchasers or any former, current
      or future director, officer, employee, agent, general or limited partner,
      manager, member, stockholder or Affiliate of any of the foregoing, whether
      by
      the enforcement of any assessment or by any legal or equitable proceeding,
      or by
      virtue of any applicable Law, it being expressly agreed and acknowledged that
      no
      personal liability whatsoever shall attach to, be imposed on or otherwise be
      incurred by any former, current or future director, officer, employee, agent,
      general or limited partner, manager, member, stockholder or Affiliate of any
      of
      the Purchasers or any former, current or future director, officer, employee,
      agent, general or limited partner, manager, member, stockholder or Affiliate
      of
      any of the foregoing, as such, for any obligations of the Purchasers under
      this
      Agreement or the Purchase Agreement or any documents or instruments delivered
      in
      connection herewith or therewith or for any claim based on, in respect of or
      by
      reason of such obligation or its creation. 

     

    18


    

    
    

    [The
      remainder of this page is
      intentionally left blank] 

     

    19


    

    
    

    IN
      WITNESS WHEREOF, the Parties
      hereto execute this Agreement, effective as of the date first above written.
      

     

    
      	
            	
            	
            	
            	
            	
            	
            
	 	 	 	 	ATLAS ENERGY RESOURCES, LLC
	
            	
            	
            	
            
	
            	 	
            	 	By:	 	
               

            
	
            	
            	
            	
            
	
            	 	
            	 	Name:	 	Matthew
              A. Jones
	
            	 	
            	 	Title:	 	Chief
              Financial Officer
	
            	
            	
            
	
            	 	
              Address for notices:

            	 	Atlas
              Energy Resources, LLC
	
            	 	
            	 	311
              Rouser Road
	
            	 	
            	 	Moon
              Township, PA 15108
	
            	 	
            	 	Fax:	 	412-262-2820
	
            	 	
            	 	Attn:	 	Matthew
              A. Jones
	
            	
            	
            
	
            	 	
              With
                copies
                to:

            	 	Ledgewood
	
            	 	
            	 	1900
              Market Street, Suite 750
	
            	 	
            	 	Philadelphia,
              PA 19103
	
            	 	
            	 	Fax:	 	215-735-2513
	
            	 	
            	 	Attn:	 	Lisa
              A. Ernst


    

    Signature
      Page to Registration
      Rights Agreement 

    

    
    

    IN
      WITNESS WHEREOF, the Parties
      hereto execute this Agreement, effective as of the date first above written.
      

     

    
      	
            	
            	
            
	Purchasers:
	
            
	Goldman,
              Sachs & Co., on behalf of its Principal
Strategies
              Group
	
            	
            
	
              By:

            	 	
              /s/

            
	
              Name:

            	 	Gaurav
              Bhandari
	
              Title:

            	 	Managing
              Director
	
            
	
              Royal
                Bank of
                Canada

              by
                its agent

              RBC
                Capital Markets
                Corporation

            
	
            	
            
	By:	 	/s/
	
              Name:
                Josef
                Muskatel

              Title:
                Director and Senior
                Counsel

            
	
            	
            
	By:	 	/s/
	
              Name:
                David
                Weiner

              Title:
                Managing
                Director

            
	
            
	Swank
              MLP Convergence Fund, LP
	
            	
            
	By:	 	/s/
	
              Name:
                Jerry V.
                Swank

              Title:
                Managing
                Partner

            
	
            
	The
              Cushing MLP Opportunity Fund I, LP
	
            	
            
	By:	 	/s/
	
              Name:
                Jerry V.
                Swank

              Title:
                Managing
                Partner

            
	
            
	ZLP
              Fund, L.P.
	
            
	By:
              Zimmer Lucas Partners, LLC, its general partner
	
            	
            
	By:	 	/s/
	
              Name:
                Craig M.
                Lucas

              Title:
                Managing
                Member

            
	
            
	Kayne
              Anderson Energy Development Company
	
            	
            
	By:	 	/s/
	
              Name:
                James C.
                Baker

              Title:
                Vice
                President

            
	
            
	Kayne
              Anderson MLP Investment Company
	
            	
            
	By:	 	/s/
	
              Name:
                James C.
                Baker

              Title:
                Vice
                President

            
	
            
	Kayne
              Anderson Energy Total Return Fund, Inc.
	
            	
            
	By:	 	/s/
	
              Name:
                James C.
                Baker

              Title:
                Vice
                President

            
	
            
	Lehman
              Brothers Inc.
	
            	
            
	By:	 	/s/
	
              Name:
                Walter G.
                Maloney

              Title:
                Managing
                Director

            
	
            
	Magnetar
              Capital Fund, LP
	
            
	By:
              Magnetar Financial LLC, its general partner
	
            	
            
	By:	 	/s/
	
              Name:
                Paul A.
                Smith

              Title:
                General
                Counsel

            
	
            
	Structured
              Finance Americas, LLC
	
            	
            
	By:	 	/s/
	
              Name:
                Sunil
                Hariani

              Title:
                VP

            
	
            	
            
	By:	 	/s/
	
              Name:
                Jill H.
                [Illegible]

              Title:
                VP

            
	
            
	LB
              I Group
	
            	
            
	By:	 	/s/
	
              Name:
                Paul H.
                Tice

              Title:
                Managing
                Director

            
	
            
	Lehman
              Brothers MLP Opportunity Fund L.P.
	
            
	By:
              Lehman Brothers MLP Opportunity Associates L.P., its general
              partner
	
            
	By:
              Lehman Brothers MLP Opportunity Associates L.L.C., its general
              partner
	
            	
            
	By:	 	/s/
	
              Name:
                Kyri Loupis

              Title:
                Senior Vice
                President

            
	
            
	Cobalt
              Partners, LP
	
            
	By:
              Cobalt Management, LLC, its General Partner
	
            	
            
	By:	 	/s/
	
              Name:
                Wayne
                Cooperman

              Title:
                Managing
                Member

            
	
            
	Cobalt
              Partners II, LP
	
            
	By:
              Cobalt Management, LLC, its General Partner
	
            	
            
	By:	 	/s/
	
              Name:
                Wayne
                Cooperman

              Title:
                Managing
                Member

            
	
            
	Guggenheim
              Portfolio Company XI, LLC
	
            
	By:
              Cobalt Capital Management, its Investment Manager
	
            	
            
	By:	 	/s/
	
              Name:
                Wayne
                Cooperman

              Title:
                President

            
	
            
	Cobalt
              Capital SPV 1 LLC
	
            
	By:
              Cobalt Management, LLC, its General Partner
	
            	
            
	By:	 	/s/
	
              Name:
                Wayne
                Cooperman

              Title:
                Managing
                Member

            
	
            
	Credit
              Suisse Management LLC
	
            	
            
	By:	 	/s/
	
              Name:
                Gerard
                Murtagh

              Title:
                Managing
                Director

            
	
            
	Sunlight
              Capital Partners, LLC
	
            	
            
	By:	 	/s/
	
              Name:
                Elliot
                Greenberg

              Title:
                Vice
                President

            
	
            
	Omega
              Advisors, Inc.*
	
            	
            
	By:	 	/s/
	
              Name:
                Denis Wong

              Title:
                Chief Operating
                Officer

            


    

     

    
      	*	solely
              in its capacity as investment manager of the following
              entities and not in its individual corporate capacity:
              


    

    Omega
      Capital Partners, L.P.


    Omega
      Capital Investors, L.P.


    Omega
      SPV Partners, L.P.


    Omega
      Equity Investors, L.P.


    Beta
      Equities, Inc. 

    GS&Co
      Profit Sharing Master
      Trust 

    Presidential
      Life Corporation


    The
      Ministers and Missionaries
      Benefit Board of American Baptist Churches 

     

    
      	
            	
            	
            
	Wingate
              Capital Ltd.
	
            
	By:
              Citadel Limited Partnership, Portfolio Manger
	By:
              Citadel Investment Group, L.L.C., its General
              Partner
	
            	
            
	By:	 	/s/
	
              Name:
                John Nagel

              Title:
                Director and Associate
                General Counsel

            
	
            
	Oz
              Offshore ATN Investors I, LLC
	By:
              OZ Overseas Fund, Ltd., its Sole Member
	By:
              OZ Management, L.L.C., its Investment Manager
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            
	
            
	Oz
              Offshore ATN Investors II, LLC
	By:
              OZ Overseas Fund II, Ltd., its Sole Member
	By:
              OZ Management, L.L.c., its Investment Manager
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            
	
            
	Oz
              Offshore ATN Investors III, LLC
	By:
              OZ Global Special Investments Intermediate Fund, L.P. its Sole
              Member
	By:
              OZ Advisors, LLC, its General Partner
	By:
              Och-Ziff Associates, LLC, its Managing Member
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            
	
            
	Oz
              Global Special Investments, L.P.
	By:
              OZ Advisors, L.L.C., its General Partner
	By:
              Och-Ziff Associates, L.L.C., its Managing Member
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            
	
            
	OZ
              Domestic Partners, L.P.
	By:
              OZ Advisors, L.L.C., its General Partner
	By:
              Och-Ziff Associates, L.L.C., its Managing Member
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            
	
            
	Oz
              Domestic Partners II, L.P.
	By:
              OZ Advisors, L.L.C., its General Partner
	By:
              Och-Ziff Associates, L.L.C., its Managing Member
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            
	
            
	GPC
              LVII, LLC
	By:
              OZ Management, L.L.C., its Investment Manager
	
            	
            
	By:	 	/s/
	
              Name:
                Joel M.
                Frank

              Title:
                Chief Financial
                Officer

            


    

    Signature
      Page to Registration
      Rights Agreement