Exhibit 4.1
                                                                     -----------

                      ALLEGHENY ENERGY SUPPLY COMPANY, LLC

                              7.80% NOTES DUE 2011

                          REGISTRATION RIGHTS AGREEMENT

                                                              New York, New York
                                                              March 15, 2001

Salomon Smith Barney Inc.
As Representative of the Initial Purchasers
c/o Salomon Smith Barney Inc.
Seven World Trade Center
New York, New York  10048

Dear Sirs:

            Allegheny Energy Supply Company, LLC, a limited liability company
formed under the laws of Delaware (the "Company"), proposes to issue and sell to
certain purchasers (the "Initial Purchasers"), upon the terms set forth in a
purchase agreement dated March 9, 2001 (the "Purchase Agreement"), its 7.80%
Notes due 2011 (the "Original Securities") relating to the initial placement of
the Original Securities (the "Initial Placement"). To induce the Initial
Purchasers to enter into the Purchase Agreement and to satisfy a condition of
your obligations thereunder, the Company agrees with you for your benefit and
the benefit of the holders from time to time of the Original Securities
(including the Initial Purchasers) (each a "Holder" and, together, the
"Holders"), as follows:

            1. DEFINITIONS. Capitalized terms used herein without definition
shall have their respective meanings set forth in the Purchase Agreement. As
used in this Agreement, the following capitalized defined terms shall have the
following meanings:

            "Act" shall mean the Securities Act of 1933, as amended, and the
rules and regulations of the Commission promulgated thereunder.

            "Affiliate" of any specified Person shall mean any other Person
that, directly or indirectly, is in control of, is controlled by, or is under
common control with, such specified Person. For purposes of this definition,
control of a Person shall mean the power, direct or indirect, to direct or cause
the direction of the management and policies of such Person whether by contract
or otherwise; and the terms "controlling" and "controlled" shall have meanings
correlative to the foregoing.

            "Broker-Dealer" shall mean any broker or dealer registered as such
under the Exchange Act.


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            "Business Day" shall mean any day other than a Saturday, a Sunday or
a legal holiday or a day on which banking institutions or trust companies are
authorized or obligated by law to close in New York City.

            "Commission" shall mean the Securities and Exchange Commission.

            "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission promulgated thereunder.

            "Exchange Offer Registration Period" shall mean the 180 day period
following the consummation of the Registered Exchange Offer, exclusive of any
period during which any stop order shall be in effect suspending the
effectiveness of the Exchange Offer Registration Statement.

            "Exchange Offer Registration Statement" shall mean a registration
statement of the Company on an appropriate form under the Act with respect to
the Registered Exchange Offer, all amendments and supplements to such
registration statement, including post-effective amendments thereto, in each
case including the Prospectus contained therein, all exhibits thereto and all
material incorporated by reference therein.

            "Exchanging Dealer" shall mean any Holder (which may include any
Initial Purchaser) that is a Broker-Dealer and elects to exchange any Original
Securities that it acquired for its own account as a result of market-making
activities or other trading activities (but not directly from the Company or any
Affiliate of the Company) for Exchange Securities.

            "Exchange Securities" shall mean debt securities of the Company
identical in all material respects to the Original Securities (except that the
cash interest and interest rate step-up provisions and the transfer restrictions
shall be modified or eliminated, as appropriate) and to be issued under the
Indenture.

            "Final Memorandum" shall have the meaning set forth in the Purchase
Agreement.

            "Holder" shall have the meaning set forth in the preamble hereto.

            "Indenture" shall mean the Indenture relating to the Securities,
dated as of March 15, 2001, between the Company and Bank One Trust Company,
N.A., as trustee, as the same may be amended from time to time in accordance
with the terms thereof.

            "Initial Placement" shall have the meaning set forth in the preamble
hereto.

            "Initial Purchaser" shall have the meaning set forth in the preamble
hereto.

            "Losses" shall have the meaning set forth in Section 6(d) hereof.

            "Majority Holders" shall mean the Holders of a majority of the
aggregate principal amount of Original Securities registered under a
Registration Statement.


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            "Managing Underwriters" shall mean the investment banker or
investment bankers and manager or managers that shall administer an underwritten
offering.

            "Original Securities" shall have the meaning set forth in the
preamble hereto.

            "Person" means any individual, corporation, or partnership, joint
venture, trust, unincorporated organization or government organization, agency
or political subdivision thereof.

            "Prospectus" shall mean the prospectus included in any Registration
Statement (including, without limitation, a prospectus that discloses
information previously omitted from a prospectus filed as part of an effective
registration statement in reliance upon Rule 430A under the Act), as amended or
supplemented by any prospectus supplement, with respect to the terms of the
offering of any portion of the Original Securities or the Exchange Securities
covered by such Registration Statement, and all amendments and supplements
thereto and all material incorporated by reference therein.

            "Purchase Agreement" shall have the meaning set forth in the
preamble hereto.

            "Registered Exchange Offer" shall mean the proposed offer of the
Company to issue and deliver to the Holders of the Original Securities that are
not prohibited by any law or policy of the Commission from participating in such
offer, in exchange for the Original Securities, a like aggregate principal
amount of the Exchange Securities.

            "Registration Statement" shall mean any Exchange Offer Registration
Statement or Shelf Registration Statement that covers any of the Original
Securities or the Exchange Securities pursuant to the provisions of this
Agreement, any amendments and supplements to such registration statement,
including post-effective amendments (in each case including the Prospectus
contained therein), all exhibits thereto and all material incorporated by
reference therein.

            "Shelf Registration" shall mean a registration effected pursuant to
Section 3 hereof.

            "Shelf Registration Period" has the meaning set forth in Section
3(b) hereof.

            "Shelf Registration Statement" shall mean a "shelf" registration
statement of the Company pursuant to the provisions of Section 3 hereof which
covers some or all of the Original Securities, on an appropriate form under Rule
415 under the Act or any similar rule that may be adopted by the Commission,
amendments and supplements to such registration statement, including
post-effective amendments, in each case including the Prospectus contained
therein, all exhibits thereto and all material incorporated by reference
therein.

            "Trustee" shall mean the trustee with respect to the Original
Securities under the Indenture.

            "underwriter" shall mean any underwriter of Original Securities in
connection with an offering thereof under a Shelf Registration Statement.


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            2. REGISTERED EXCHANGE OFFER. (a) The Company shall use its
reasonable best efforts to cause the Exchange Offer Registration Statement to
become effective under the Act within 270 days of the date of the original
issuance of the Original Securities (or if such 270th day is not a Business Day,
the next succeeding Business Day).

            (b) Upon the effectiveness of the Exchange Offer Registration
Statement, the Company shall promptly commence the Registered Exchange Offer, it
being the objective of such Registered Exchange Offer to enable each Holder
electing to exchange Original Securities for Exchange Securities (assuming that
such Holder is not an Affiliate of the Company, acquires the Exchange Securities
in the ordinary course of such Holder's business, has no arrangements with any
Person to participate in the distribution of the Exchange Securities and is not
prohibited by any law or policy of the Commission from participating in the
Registered Exchange Offer) to trade such Exchange Securities from and after
their receipt without any limitations or restrictions under the Act and without
material restrictions under the securities laws of a substantial proportion of
the several states of the United States.

            (c) In connection with the Registered Exchange Offer, the Company
shall:

                (i) mail to each Holder a copy of the Prospectus forming part of
      the Exchange Offer Registration Statement, together with an appropriate
      letter of transmittal and related documents;

                (ii) keep the Registered Exchange Offer open for not less than
      30 days and not more than 45 days after the date notice thereof is mailed
      to the Holders (or, in each case, longer if required by applicable law);

                (iii) use its reasonable best efforts to keep the Exchange Offer
      Registration Statement continuously effective under the Act, supplemented
      and amended as required, under the Act to ensure that it is available for
      sales of Exchange Securities by Exchanging Dealers during the Exchange
      Offer Registration Period;

                (iv) utilize the services of a depositary for the Registered
      Exchange Offer with an address in the Borough of Manhattan in New York
      City, which may be the Company or the Trustee or an Affiliate of either of
      them;

                (v) permit Holders to withdraw tendered Original Securities at
      any time prior to the close of business, New York time, on the last
      Business Day on which the Registered Exchange Offer is open; and

                (vi) prior to effectiveness of the Exchange Offer Registration
      Statement, provide a supplemental letter to the Commission (A) stating
      that the Company is conducting the Registered Exchange Offer in reliance
      on the position of the Commission in EXXON CAPITAL HOLDINGS CORPORATION
      (pub. avail. May 13, 1988), MORGAN STANLEY AND CO., INC. (pub. avail. June
      5, 1991); and (B) including a representation that the Company has not
      entered into any arrangement or understanding with any Person to
      distribute the Exchange Securities to be received in the Registered
      Exchange Offer and that, to the best of the Company's information and
      belief, each Holder participating in the Registered Exchange Offer is
      acquiring the Exchange Securities in the ordinary course of


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      business and has no arrangement or understanding with any Person to
      participate in the distribution of the Exchange Securities or, if it is an
      Affiliate of the Company, it will comply with the registration and
      prospectus delivery requirements of the Act to the extent applicable.

            (d) As soon as practicable after the close of the Registered
Exchange Offer, the Company shall:

                (i) accept for exchange all Original Securities tendered and not
      validly withdrawn pursuant to the Registered Exchange Offer;

                (ii) deliver to the Trustee for cancellation in accordance with
      Section 4(r) all Original Securities so accepted for exchange; and

                (iii) cause the Trustee promptly to authenticate and deliver to
      each Holder of Original Securities a principal amount of Exchange
      Securities equal to the principal amount of the Original Securities of
      such Holder so accepted for exchange.

            (e) Each Holder hereby acknowledges and agrees that any
Broker-Dealer and any such Holder using the Registered Exchange Offer to
participate in a distribution of the Exchange Securities (x) could not under
Commission policy as in effect on the date of this Agreement rely on the
position of the Commission in MORGAN STANLEY AND CO., INC. (pub. avail. June 5,
1991) and EXXON CAPITAL HOLDINGS CORPORATION (pub. avail. May 13, 1988), as
interpreted in the Commission's letter to Shearman & Sterling dated July 2, 1993
and similar no-action letters; and (y) must comply with the registration and
prospectus delivery requirements of the Act in connection with any secondary
resale transaction and such sales must be covered by an effective registration
statement containing the selling security holder information required by Item
507 or 508, as applicable, of Regulation S-K under the Act if the resales are of
Exchange Securities obtained by such Holder in exchange for Original Securities
acquired by such Holder directly from the Company or one of its Affiliates.
Accordingly, each Holder participating in the Registered Exchange Offer shall be
required to represent to the Company that, at the time of the consummation of
the Registered Exchange Offer:

                (i) any Exchange Securities received by such Holder will be
      acquired in the ordinary course of business;

                (ii) such Holder will have no arrangement or understanding with
      any Person to participate in the distribution of the Original Securities
      or the Exchange Securities within the meaning of the Act; and

                (iii) such Holder is not an Affiliate of the Company.

            (f) If any Initial Purchaser determines that it is not eligible to
participate in the Registered Exchange Offer with respect to the exchange of
Original Securities constituting any portion of an unsold allotment, at the
request of such Initial Purchaser, the Company shall issue and deliver to the
Person purchasing Exchange Securities registered under a Shelf Registration
Statement as contemplated by Section 3 hereof from such Initial Purchaser, in
exchange for such Original Securities, a like principal amount of Exchange
Securities. The

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Company shall use its best efforts to cause the CUSIP Service Bureau to issue
the same CUSIP number for such Exchange Securities as for Exchange Securities
issued pursuant to the Registered Exchange Offer.

            3. SHELF REGISTRATION. (a) If (i) due to any change in law or
applicable interpretations thereof by the Commission's staff, the Company
determines upon advice of its outside counsel that it is not permitted to effect
the Registered Exchange Offer as contemplated by Section 2 hereof; or (ii) for
any other reason the Registered Exchange Offer is not declared effective within
270 days after the date hereof or consummated within 315 days of the date
hereof; or (iii) any Initial Purchaser so requests with respect to Original
Securities that are not eligible to be exchanged for Exchange Securities in the
Registered Exchange Offer and that are held by it following consummation of the
Registered Exchange Offer, the Company shall effect a Shelf Registration
Statement in accordance with subsection (b) below.

            (b) (i) The Company shall as promptly as practicable (but in no
event more than 90 days after so required or requested pursuant to this Section
3), file with the Commission and thereafter shall use its reasonable best
efforts to cause to be declared effective under the Act a Shelf Registration
Statement relating to the offer and sale of the Original Securities by the
Holders thereof from time to time in accordance with the methods of distribution
elected by such Holders and set forth in such Shelf Registration Statement;
provided, however, that no Holder (other than an Initial Purchaser) shall be
entitled to have the Original Securities held by it covered by such Shelf
Registration Statement unless such Holder agrees in writing to be bound by all
of the provisions of this Agreement applicable to such Holder.

                (ii) The Company shall use its best efforts to keep the Shelf
      Registration Statement continuously effective, supplemented and amended as
      required by the Act, in order to permit the Prospectus forming part
      thereof to be usable by Holders until the earlier of all the Original
      Securities covered by the Shelf Registration Statement being sold pursuant
      to the Shelf Registration Statement or such Original Securities becoming
      freely tradable pursuant to Rule 144(k) of the Act (in any such case, such
      period being called the "Shelf Registration Period"). The Company shall be
      deemed not to have used its best efforts to keep the Shelf Registration
      Statement effective during the requisite period if it voluntarily takes
      any action that would result in Holders of Original Securities covered
      thereby not being able to offer and sell such Original Securities during
      that period, unless (A) such action is required by applicable law; or (B)
      such action is taken by the Company in good faith and for valid business
      reasons (not including avoidance of the Company's obligations hereunder),
      including the acquisition or divestiture of assets, so long as the Company
      promptly thereafter complies with the requirements of Section 4(k) hereof,
      if applicable.

            4. ADDITIONAL REGISTRATION PROCEDURES. In connection with any Shelf
Registration Statement and, to the extent applicable, any Exchange Offer
Registration Statement, the following provisions shall apply.

            (a) The Company shall:


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                (i) furnish to you, not less than five Business Days prior to
      the filing thereof with the Commission, a copy of any Exchange Offer
      Registration Statement and any Shelf Registration Statement, and each
      amendment thereof and each amendment or supplement, if any, to the
      Prospectus included therein (including all documents incorporated by
      reference therein after the initial filing) and shall use its best efforts
      to reflect in each such document, when so filed with the Commission, such
      comments as you reasonably propose;

                (ii) include the information set forth in Annex A hereto on the
      facing page of the Exchange Offer Registration Statement, in Annex B
      hereto in the forepart of the Exchange Offer Registration Statement in a
      section setting forth details of the Exchange Offer, in Annex C hereto in
      the underwriting or plan of distribution section of the Prospectus
      contained in the Exchange Offer Registration Statement, and in Annex D
      hereto in the letter of transmittal delivered pursuant to the Registered
      Exchange Offer;

                (iii) if requested by an Initial Purchaser, include the
      information required by Item 507 or 508 of Regulation S-K, as applicable,
      in the Prospectus contained in the Exchange Offer Registration Statement;
      and

                (iv) in the case of a Shelf Registration Statement, include the
      names of the Holders that propose to sell Original Securities pursuant to
      the Shelf Registration Statement as selling security holders.

            (b) The Company shall ensure that:

                (i) any Registration Statement and any amendment thereto and any
      Prospectus forming part thereof and any amendment or supplement thereto
      complies in all material respects with the Act and the rules and
      regulations thereunder; and

                (ii) any Registration Statement and any amendment thereto does
      not, when it becomes effective, 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.

            (c) The Company shall advise you, the Holders of Original Securities
covered by any Shelf Registration Statement and any Exchanging Dealer under any
Exchange Offer Registration Statement that has provided in writing to the
Company a telephone or facsimile number and address for notices, and, if
requested by you or any such Holder or Exchanging Dealer, shall confirm such
advice in writing (which notice pursuant to clauses (ii)-(v) hereof shall be
accompanied by an instruction to suspend the use of the Prospectus until the
Company shall have remedied the basis for such suspension):

                (i) when a Registration Statement and any amendment thereto has
      been filed with the Commission and when the Registration Statement or any
      post-effective amendment thereto has become effective;

                (ii) of any request by the Commission for any amendment or
      supplement to the Registration Statement or the Prospectus or for
      additional information;


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                (iii) of the issuance by the Commission of any stop order
      suspending the effectiveness of the Registration Statement or the
      initiation of any proceedings for that purpose;

                (iv) of the receipt by the Company of any notification with
      respect to the suspension of the qualification of the securities included
      therein for sale in any jurisdiction or the initiation of any proceeding
      for such purpose; and

                (v) of the happening of any event that requires any change in
      the Registration Statement or the Prospectus so that, as of such date, the
      statements therein are not misleading and do not omit to state a material
      fact required to be stated therein or necessary to make the statements
      therein (in the case of the Prospectus, in the light of the circumstances
      under which they were made) not misleading.

Each Holder of Original Securities agrees by acquisition of such Original
Securities that, upon actual receipt of any notice from the Company of the
happening of any event of the kind described in Section 4(c)(ii), (iii), (iv),
and (v) hereof, such Holder will forthwith discontinue any and all dispositions
of such Original Securities by means of the Registration Statement or Prospectus
until such Holder's receipt of the copies of the supplemented or amended
Prospectus contemplated by Section 4(b), or until it is advised in writing by
the Company that the use of the applicable Prospectus may be resumed, and has
received copies of any amendments or supplements thereto provided, however, that
this paragraph shall not prohibit any Holder from engaging in dispositions of
the Original Securities through means other than pursuant to the Registration
Statement or Prospectus, as long as such dispositions comply with applicable
laws.

            (d) The Company shall use its reasonable best efforts to obtain the
withdrawal of any order suspending the effectiveness of any Registration
Statement or the qualification of the securities therein for sale in any
jurisdiction at the earliest possible time.

            (e) The Company shall furnish to each Holder of Original Securities
covered by any Shelf Registration Statement, without charge, at least one copy
of such Shelf Registration Statement and any post-effective amendment thereto,
including all material incorporated therein by reference, and, if the Holder so
requests in writing, all exhibits thereto (including exhibits incorporated by
reference therein).

            (f) The Company shall, during the Shelf Registration Period, deliver
to each Holder of Original Securities covered by any Shelf Registration
Statement, without charge, as many copies of the Prospectus (including each
preliminary Prospectus) included in such Shelf Registration Statement and any
amendment or supplement thereto as such Holder may reasonably request. The
Company consents to the use of the Prospectus or any amendment or supplement
thereto by each of the selling Holders of securities in connection with the
offering and sale of the securities covered by the Prospectus, or any amendment
or supplement thereto, included in the Shelf Registration Statement.

            (g) The Company shall furnish to each Exchanging Dealer which so
requests, without charge, at least one copy of the Exchange Offer Registration
Statement and any post-effective amendment thereto, including all material
incorporated by reference therein, and, if the


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Exchanging Dealer so requests in writing, all exhibits thereto (including
exhibits incorporated by reference therein).

            (h) The Company shall promptly deliver to each Initial Purchaser,
each Exchanging Dealer and each other Person required to deliver a Prospectus
during the Exchange Offer Registration Period, without charge, as many copies of
the Prospectus included in such Exchange Offer Registration Statement and any
amendment or supplement thereto as any such Person may reasonably request. The
Company consents to the use of the Prospectus or any amendment or supplement
thereto by any Initial Purchaser, any Exchanging Dealer and any such other
Person that may be required to deliver a Prospectus following the Registered
Exchange Offer in connection with the offering and sale of the Exchange
Securities covered by the Prospectus, or any amendment or supplement thereto,
included in the Exchange Offer Registration Statement.

            (i) Prior to the Registered Exchange Offer or any other offering of
Original Securities or Exchange Securities pursuant to any Registration
Statement, the Company shall arrange, if necessary, for the qualification of the
Original Securities or the Exchange Securities for sale under the laws of such
jurisdictions as any Holder shall reasonably request and will maintain such
qualification in effect so long as required; provided that in no event shall the
Company be obligated to qualify to do business in any jurisdiction where it is
not then so qualified or to take any action that would subject it to service of
process in suits, other than those arising out of the Initial Placement, the
Registered Exchange Offer or any offering pursuant to a Shelf Registration
Statement, in any such jurisdiction where it is not then so subject.

            (j) The Company shall cooperate with the Holders of Original
Securities to facilitate the timely preparation and delivery of certificates
representing Exchange Securities or Original Securities to be issued or sold
pursuant to any Registration Statement free of any restrictive legends and in
such denominations and registered in such names as Holders may request.

            (k) Upon the occurrence of any event contemplated by subsections
(c)(ii) through (v) above, the Company shall promptly prepare a post-effective
amendment to the applicable Registration Statement or an amendment or supplement
to the related Prospectus or file any other required document so that, as
thereafter delivered to Initial Purchasers of the securities included therein,
the Prospectus will not include an untrue statement of a material fact or omit
to state any material fact necessary to make the statements therein, in the
light of the circumstances under which they were made, not misleading. In such
circumstances, the period of effectiveness of the Exchange Offer Registration
Statement provided for in Section 2 shall be extended by the number of days from
and including the date of the giving of a notice of suspension pursuant to
Section 4(c) to and including the date when the Initial Purchasers, the Holders
of the Original Securities and any known Exchanging Dealer shall have received
such amended or supplemented Prospectus pursuant to this Section.

            (l) Not later than the effective date of any Registration Statement,
the Company shall provide a CUSIP number for the Original Securities or the
Exchange Securities, as the case may be, registered under such Registration
Statement and provide the Trustee with

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printed certificates for such Original Securities or Exchange Securities, in a
form eligible for deposit with The Depository Trust Company.

            (m) The Company shall comply with all applicable rules and
regulations of the Commission and shall make generally available to its security
holders as soon as practicable after the effective date of the applicable
Registration Statement an earnings statement satisfying the provisions of
Section 11(a) of the Act.

            (n) The Company shall cause the Indenture to be qualified under the
Trust Indenture Act in a timely manner.

            (o) The Company may require each Holder of securities to be sold
pursuant to any Shelf Registration Statement to furnish to the Company such
information regarding the Holder and the distribution of such securities as the
Company may reasonably require for inclusion in such Registration Statement. The
Company will send a notice of such required information at least 30 days prior
to the deadline for providing such information and give holders 28 days to
respond to the notices. The Company may exclude from such Shelf Registration
Statement the Original Securities of any Holder that fails to furnish such
information within the time specified in the previous sentence.

            (p) In the case of any Shelf Registration Statement, the Company
shall enter into such and take all other appropriate actions (including if
requested an underwriting agreement in customary form) in order to expedite or
facilitate the registration or the disposition of the Securities, and in
connection therewith, if an underwriting agreement is entered into, cause the
same to contain indemnification provisions and procedures no less favorable than
those set forth in Section 6 (or such other provisions and procedures acceptable
to the Majority Holders and the Managing Underwriters, if any, with respect to
all parties to be indemnified pursuant to Section 6).

            (q) In the case of any Shelf Registration Statement, the Company
shall:

                (i) make reasonably available for inspection by the Holders of
      Original Securities to be registered thereunder, any underwriter
      participating in any disposition pursuant to such Registration Statement,
      and any attorney, accountant or other agent retained by the Holders or any
      such underwriter all relevant financial and other records, pertinent
      corporate documents and properties of the Company and its subsidiaries;

                (ii) cause the Company's officers, directors and employees to
      supply all relevant information reasonably requested by the Holders or any
      such underwriter, attorney, accountant or agent in connection with any
      such Registration Statement as is customary for similar due diligence
      examinations; PROVIDED, HOWEVER, that any information that is designated
      in writing by the Company, in good faith, as confidential at the time of
      delivery of such information shall be kept confidential by the Holders or
      any such underwriter, attorney, accountant or agent, unless such
      disclosure is made in connection with a court proceeding or required by
      law, or such information becomes

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<PAGE>

      available to the public generally or through a third party without an
      accompanying obligation of confidentiality;

                (iii) make such representations and warranties to the Holders of
      Original Securities registered thereunder and the underwriters, if any, in
      form, substance and scope as are customarily made by issuers to
      underwriters in primary underwritten offerings and covering matters
      including, but not limited to, those set forth in the Purchase Agreement;

                (iv) obtain opinions of counsel to the Company and updates
      thereof (which counsel and opinions (in form, scope and substance) shall
      be reasonably satisfactory to the Managing Underwriters, if any) addressed
      to each selling Holder and the underwriters, if any, covering such matters
      as are customarily covered in opinions requested in underwritten offerings
      and such other matters as may be reasonably requested by such Holders and
      underwriters;

                (v) obtain "cold comfort" letters and updates thereof from the
      independent certified public accountants of the Company (and, if
      necessary, any other independent certified public accountants of any
      subsidiary of the Company or of any business acquired by the Company for
      which financial statements and financial data are, or are required to be,
      included in the Registration Statement), addressed to each selling Holder
      of Original Securities registered thereunder and the underwriters, if any,
      in customary form and covering matters of the type customarily covered in
      "cold comfort" letters in connection with primary underwritten offerings;
      and

                (vi) deliver such documents and certificates as may be
      reasonably requested by the Majority Holders and the Managing
      Underwriters, if any, including those to evidence compliance with Section
      4(k) and with any customary conditions contained in the underwriting
      agreement or other agreement entered into by the Company.

The actions set forth in clauses (iii), (iv), (v) and (vi) of this Section shall
be performed at (A) the effectiveness of such Registration Statement and each
post-effective amendment thereto; and (B) each closing under any underwriting or
similar agreement as and to the extent required thereunder.

            (r) If a Registered Exchange Offer is to be consummated, upon
delivery of the Original Securities by Holders to the Company (or to such other
Person as directed by the Company) in exchange for the Exchange Securities, the
Company shall mark, or cause to be marked, on the Original Securities so
exchanged that such Original Securities are being canceled in exchange for the
Exchange Securities. In no event shall the Original Securities be marked as paid
or otherwise satisfied.

            (s) The Company will use its reasonable best efforts (i) if the
Original Securities have been rated prior to the initial sale of such
Securities, to confirm such ratings will apply to the Original Securities or the
Exchange Securities, as the case may be, covered by a Registration Statement; or
(ii) if the Original Securities were not previously rated, to cause the



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Original Securities covered by a Registration Statement to be rated with at
least one nationally recognized statistical rating agency, if so requested by
Majority Holders with respect to the related Registration Statement or by any
Managing Underwriters.

            (t) In the event that any Broker-Dealer shall underwrite any
Original Security or participate as a member of an underwriting syndicate or
selling group or "assist in the distribution" (within the meaning of the Rules
of Fair Practice and the By-Laws of the National Association of Securities
Dealers, Inc.) thereof, whether as a Holder of such Original Securities or as an
underwriter, a placement or sales agent or a broker or dealer in respect
thereof, or otherwise, the Company will assist such Broker-Dealer in complying
with the requirements of such Rules and By-Laws, including, without limitation,
by:

                (i) if such Rules or By-Laws shall so require, engaging a
      "qualified independent underwriter" (as defined in such Rules) to
      participate in the preparation of the Registration Statement, to exercise
      usual standards of due diligence with respect thereto and, if any portion
      of the offering contemplated by such Registration Statement is an
      underwritten offering or is made through a placement or sales agent, to
      recommend the yield of such Securities;

                (ii) indemnifying any such qualified independent underwriter to
      the extent of the indemnification of underwriters provided in Section 6
      hereof; and

                (iii) providing such information to such Broker-Dealer as may be
      required in order for such Broker-Dealer to comply with the requirements
      of such Rules.

            (u) The Company shall use its reasonable best efforts to take all
other steps necessary to effect the registration of the Original Securities or
the Exchange Securities, as the case may be, covered by a Registration
Statement.

            5. REGISTRATION EXPENSES. The Company shall bear all expenses
incurred in connection with the performance of its obligations under Sections 2,
3 and 4 hereof and, in the event of any Shelf Registration Statement, will
reimburse the Holders for the reasonable fees and disbursements of one law firm
or counsel designated by the Majority Holders to act as counsel for the Holders
in connection therewith, and, in the case of any Exchange Offer Registration
Statement, will reimburse the Initial Purchasers for the reasonable fees and
disbursements of one law firm or counsel acting in connection therewith.

            6. INDEMNIFICATION AND CONTRIBUTION. (a) The Company agrees to
indemnify and hold harmless each Holder of Original Securities or Exchange
Securities, as the case may be, covered by any Registration Statement (including
each Initial Purchaser and, with respect to any Prospectus delivery as
contemplated in Section 4(h) hereof, each Exchanging Dealer), the directors,
officers, employees and agents of each such Holder and each Person who controls
any such Holder within the meaning of either the Act or the Exchange Act against
any and all losses, claims, damages or liabilities, joint or several, to which
they or any of them may become subject under the Act, the Exchange Act or other
Federal or state statutory law or regulation, at common law or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon any untrue statement of a material fact
contained in the

                                       13
<PAGE>




Registration Statement as originally filed or in any amendment thereof, or in
any preliminary Prospectus or the Prospectus, or in any amendment thereof or
supplement thereto, or arise out of or are based upon the omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading, and agrees to reimburse each such indemnified party, as
incurred, for any legal or other expenses reasonably incurred by them in
connection with investigating or defending any such loss, claim, damage,
liability or action; PROVIDED, HOWEVER, that the Company will not be liable in
any such case to the extent that any such loss, claim, damage or liability
arises out of or is based upon any such untrue statement or omission made
therein in reliance upon and in conformity with written information furnished to
the Company by or on behalf of any such Holder specifically for inclusion
therein. This indemnity agreement will be in addition to any liability which the
Company may otherwise have.

            The Company also agrees to indemnify or contribute as provided in
Section 6(d) to Losses of any underwriter of Original Securities registered
under a Shelf Registration Statement, their directors, officers, employees or
agents and each Person who controls such underwriter on substantially the same
basis as that of the indemnification of the Initial Purchasers and the selling
Holders provided in this Section 6(a) and shall, if requested by any Holder,
enter into an underwriting agreement reflecting such agreement, as provided in
Section 4(p) hereof.

            (b) Each Holder of securities covered by a Registration Statement
(including each Initial Purchaser and, with respect to any Prospectus delivery
as contemplated in Section 4(h) hereof, each Exchanging Dealer) severally and
not jointly agrees to indemnify and hold harmless the Company, each of its
directors and each of its officers who signs such Registration Statement and
each Person who controls the Company within the meaning of either the Act or the
Exchange Act, to the same extent as the foregoing indemnity from the Company to
each such Holder, but only with reference to written information relating to
such Holder furnished to the Company by or on behalf of such Holder specifically
for inclusion in the documents referred to in the foregoing indemnity. This
indemnity agreement will be in addition to any liability which any such Holder
may otherwise have.

            (c) Promptly after receipt by an indemnified party under this
Section 6 or notice of the commencement of any action, such indemnified party
will, if a claim in respect thereof is to be made against the indemnifying party
under this Section, notify the indemnifying party in writing of the commencement
thereof; but the failure so to notify the indemnifying party (i) will not
relieve it from liability under paragraph (a) or (b) above unless and to the
extent it did not otherwise learn of such action and such failure results in the
forfeiture by the indemnifying party of substantial rights and defenses; and
(ii) will not, in any event, relieve the indemnifying party from any obligations
to any indemnified party other than the indemnification obligation provided in
paragraph (a) or (b) above. The indemnifying party shall be entitled to appoint
counsel of the indemnifying party's choice at the indemnifying party's expense
to represent the indemnified party in any action for which indemnification is
sought (in which case the indemnifying party shall not thereafter be responsible
for the fees and expenses of any separate counsel retained by the indemnified
party or parties except as set forth below); PROVIDED, HOWEVER, that such
counsel shall be satisfactory to the indemnified party. Notwithstanding the
indemnifying party's election to appoint counsel to represent the indemnified
party in an action, the indemnified party shall have the right to employ
separate counsel (including local counsel),

                                       14
<PAGE>

and the indemnifying party shall bear the reasonable fees, costs and expenses of
such separate counsel if (i) the use of counsel chosen by the indemnifying party
to represent the indemnified party would present such counsel with a conflict of
interest; (ii) the actual or potential defendants in, or targets of, any such
action include both the indemnified party and the indemnifying party and the
indemnified party shall have reasonably concluded that there may be legal
defenses available to it and/or other indemnified parties which are different
from or additional to those available to the indemnifying party; (iii) the
indemnifying party shall not have employed counsel satisfactory to the
indemnified party to represent the indemnified party within a reasonable time
after notice of the institution of such action; or (iv) the indemnifying party
shall authorize the indemnified party to employ separate counsel at the expense
of the indemnifying party. An indemnifying party will not, without the prior
written consent of the indemnified parties, settle or compromise or consent to
the entry of any judgment with respect to any pending or threatened claim,
action, suit or proceeding in respect of which indemnification or contribution
may be sought hereunder (whether or not the indemnified parties are actual or
potential parties to such claim or action) unless such settlement, compromise or
consent includes an unconditional release of each indemnified party from all
liability arising out of such claim, action, suit or proceeding.

            (d) In the event that the indemnity provided in paragraph (a) or (b)
of this Section is unavailable to or insufficient to hold harmless an
indemnified party for any reason, then each applicable indemnifying party shall
have a joint and several obligation to contribute to the aggregate losses,
claims, damages and liabilities (including legal or other expenses reasonably
incurred in connection with investigating or defending same) (collectively
"Losses") to which such indemnified party may be subject in such proportion as
is appropriate to reflect the relative benefits received by such indemnifying
party, on the one hand, and such indemnified party, on the other hand, from the
Initial Placement and the Registration Statement which resulted in such Losses;
PROVIDED, HOWEVER, that in no case shall any Initial Purchaser or any subsequent
Holder of any Original Security or Exchange Security be responsible, in the
aggregate, for any amount in excess of the purchase discount or commission
applicable to such Original Security, or in the case of a Exchange Security,
applicable to the Original Security that was exchangeable into such Exchange
Security, as set forth on the cover page of the Final Memorandum, nor shall any
underwriter be responsible for any amount in excess of the underwriting discount
or commission applicable to the securities purchased by such underwriter under
the Registration Statement which resulted in such Losses. If the allocation
provided by the immediately preceding sentence is unavailable for any reason,
the indemnifying party and the indemnified party shall contribute in such
proportion as is appropriate to reflect not only such relative benefits but also
the relative fault of such indemnifying party, on the one hand, and such
indemnified party, on the other hand, in connection with the statements or
omissions which resulted in such Losses as well as any other relevant equitable
considerations. Benefits received by the Company shall be deemed to be equal to
the sum of (x) the total net proceeds from the Initial Placement (before
deducting expenses) as set forth on the cover page of the Final Memorandum and
(y) the total amount of additional interest which the Company was not required
to pay as a result of registering the securities covered by the Registration
Statement which resulted in such Losses. Benefits received by the Initial
Purchasers shall be deemed to be equal to the total purchase discounts and
commissions as set forth on the cover page of the Final Memorandum, and benefits
received by any other Holders shall be deemed to be equal to the value of
receiving Original Securities, registered under the Act. Benefits received by
any underwriter shall be deemed to be equal to the total underwriting discounts
and commissions, as

                                       15
<PAGE>


set forth on the cover page of the Prospectus forming a part of the Registration
Statement which resulted in such Losses. Relative fault shall be determined by
reference to, among other things, whether any alleged untrue statement or
omission relates to information provided by the indemnifying party, on the one
hand, or by the indemnified party, on the other hand, the intent of the parties
and their relative knowledge, access to information and opportunity to correct
or prevent such untrue statement or omission. The parties agree that it would
not be just and equitable if contribution were determined by pro rata allocation
(even if the Holders were treated as one entity for such purpose) or any other
method of allocation which does not take account of the equitable considerations
referred to above. Notwithstanding the provisions of this paragraph (d), no
Person guilty of fraudulent misrepresentation (within the meaning of Section
11(f) of the Act) shall be entitled to contribution from any Person who was not
guilty of such fraudulent misrepresentation. For purposes of this Section, each
Person who controls a Holder within the meaning of either the Act or the
Exchange Act and each director, officer, employee and agent of such Holder shall
have the same rights to contribution as such Holder, and each Person who
controls the Company within the meaning of either the Act or the Exchange Act,
each officer of the Company who shall have signed the Registration Statement and
each director of the Company shall have the same rights to contribution as the
Company, subject in each case to the applicable terms and conditions of this
paragraph (d).

            (e) The provisions of this Section will remain in full force and
effect, regardless of any investigation made by or on behalf of any Holder or
the Company or any of the officers, directors or controlling Persons referred to
in this Section hereof, and will survive the sale by a Holder of securities
covered by a Registration Statement.

            7. UNDERWRITTEN REGISTRATIONS. (a) If any of the Original Securities
covered by any Shelf Registration Statement are to be sold in an underwritten
offering, the Managing Underwriters shall be selected by the Majority Holders,
provided that such Managing Underwriters shall be reasonably satisfactory to the
Company.

            (b) No Person may participate in any underwritten offering pursuant
to any Shelf Registration Statement, unless such Person (i) agrees to sell such
Person's Original Securities, on the basis reasonably provided in any
underwriting arrangements approved by the Persons entitled hereunder to approve
such arrangements; and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements.

            8. NO INCONSISTENT AGREEMENTS. The Company has not, as of the date
hereof, entered into, nor shall it, on or after the date hereof, enter into, any
agreement with respect to its securities that is inconsistent with the rights
granted to the Holders herein or otherwise conflicts with the provisions hereof.

            9. AMENDMENTS AND WAIVERS. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, qualified,
modified or supplemented, and waivers or consents to departures from the
provisions hereof may not be given, unless the Company has obtained the written
consent of the Majority Holders (or, after the consummation of any Registered
Exchange Offer in accordance with Section 2 hereof, of Exchange Securities);
PROVIDED that, with respect to any matter that directly or indirectly affects
the rights of any Initial

                                       16
<PAGE>


Purchaser hereunder, the Company shall obtain the written consent of each such
Initial Purchaser against which such amendment, qualification, supplement,
waiver or consent is to be effective. Notwithstanding the foregoing (except the
foregoing proviso), a waiver or consent to departure from the provisions hereof
with respect to a matter that relates exclusively to the rights of Holders whose
Original Securities are being sold pursuant to a Registration Statement and that
does not directly or indirectly affect the rights of other Holders may be given
by the Majority Holders, determined on the basis of Original Securities, being
sold rather than registered under such Registration Statement.

            10. NOTICES. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, first-class mail,
telex, telecopier or air courier guaranteeing overnight delivery:

            (a) if to a Holder, at the most current address given by such holder
to the Company in accordance with the provisions of this Section, which address
initially is, with respect to each Holder, the address of such Holder maintained
by the Registrar under the Indenture, with a copy in like manner to Salomon
Smith Barney Inc.;

            (b) if to you, initially at the respective addresses set forth in
the Purchase Agreement; and

            (c) if to the Company, initially at its address set forth in the
Purchase Agreement.

            All such notices and communications shall be deemed to have been
duly given when received.

            The Initial Purchasers or the Company by notice to the other parties
may designate additional or different addresses for subsequent notices or
communications.

            11. SUCCESSORS. This Agreement shall inure to the benefit of and be
binding upon the successors and assigns of each of the parties, including,
without the need for an express assignment or any consent by the Company
thereto, subsequent Holders of Original Securities and the Exchange Securities.
The Company hereby agrees to extend the benefits of this Agreement to any Holder
of Original Securities and the Exchange Securities, and any such Holder may
specifically enforce the provisions of this Agreement as if an original party
hereto.

            12. COUNTERPARTS. This agreement may be in signed counterparts, each
of which shall an original and all of which together shall constitute one and
the same agreement.

            13. HEADINGS. The headings used herein are for convenience only and
shall not affect the construction hereof.

            14. APPLICABLE LAW. This Agreement shall be governed by and
construed in accordance with the laws of the State of New York applicable to
contracts made and to be performed in the State of New York.


                                       17
<PAGE>


            15. SEVERABILITY. In the event that any one of more of the
provisions contained herein, or the application thereof in any circumstances, is
held invalid, illegal or unenforceable in any respect for any reason, the
validity, legality and enforceability of any such provision in every other
respect and of the remaining provisions hereof shall not be in any way impaired
or affected thereby, it being intended that all of the rights and privileges of
the parties shall be enforceable to the fullest extent permitted by law.

            16. SECURITIES HELD BY THE COMPANY, ETC. Whenever the consent or
approval of Holders of a specified percentage of principal amount of Original
Securities or Exchange Securities is required hereunder, Original Securities or
Exchange Securities, as applicable, held by the Company or its Affiliates (other
than subsequent Holders of Original Securities or Exchange Securities if such
subsequent Holders are deemed to be Affiliates solely by reason of their
holdings of such Original Securities or Exchange Securities) shall not be
counted in determining whether such consent or approval was given by the Holders
of such required percentage.


                                       18
<PAGE>

            If the foregoing is in accordance with your understanding of our
agreement, please sign and return to us the enclosed duplicate hereof, whereupon
this letter and your acceptance shall represent a building agreement among the
Company and the several Initial Purchasers.

                                            Very truly yours,

                                            ALLEGHENY ENERGY SUPPLY COMPANY, LLC


                                            By:  /s/    Thomas K. Henderson
                                                -------------------------------
                                                Name:   Thomas K. Henderson
                                                Title:  Vice President


The foregoing Agreement is hereby confirmed and
accepted as of the date first above written.

By:  SALOMON SMITH BARNEY INC.


By:  /s/     Peter H. Kind
     -------------------------
     Name:   Peter H. Kind
     Title:  Managing Director



                                       19
<PAGE>

                                                                       ANNEX A

            Each Broker-Dealer that receives Exchange Securities for its own
account pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of such Exchange Securities. The Letter
of Transmittal states that by so acknowledging and by delivering a prospectus, a
Broker-Dealer will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act. This Prospectus, as it may be amended or
supplemented from time to time, may be used by a Broker-Dealer in connection
with resales of Exchange Securities received in exchange for Original Securities
where such Original Securities were acquired by such Broker-Dealer as a result
of market-making activities or other trading activities. The Company has agreed
that, starting on the Expiration Date (as defined herein) and ending on the
close of business 180 days after the Expiration Date, it will make this
Prospectus available to any Broker-Dealer for use in connection with any such
resale. See "Plan of Distribution".



                                       20
<PAGE>

                                                                       ANNEX B

            Each Broker-Dealer that receives Exchange Securities for its own
account in exchange for Original Securities, where such Original Securities were
acquired by such Broker-Dealer as a result of market-making activities or other
trading activities, must acknowledge that it will deliver a prospectus in
connection with any resale of such Exchange Securities. See "Plan of
Distribution".


                                       21
<PAGE>

                                                                       ANNEX C

                              PLAN OF DISTRIBUTION

            Each Broker-Dealer that receives Exchange Securities for its own
account pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of such Exchange Securities. This
Prospectus, as it may be amended or supplemented from time to time, may be used
by a Broker-Dealer in connection with resales of Exchange Securities received in
exchange for Original Securities where such Original Securities were acquired as
a result of market-making activities or other trading activities. The Company
has agreed that, starting on the Expiration Date and ending on the close of
business 180 days after the Expiration Date, it will make this Prospectus, as
amended or supplemented, available to any Broker-Dealer for use in connection
with any such resale. In addition, until [180 days after issue date], all
dealers effecting transactions in the Exchange Securities may be required to
deliver a prospectus.

            The Company will not receive any proceeds from any sale of Exchange
Securities by brokers-dealers. Exchange Securities received by Broker-Dealers
for their own account pursuant to the Exchange Offer may be sold from time to
time in one or more transactions in the over-the-counter market, in negotiated
transactions, through the writing of options on the Exchange Securities or a
combination of such methods of resale, at market prices prevailing at the time
of resale, at prices related to such prevailing market prices or negotiated
prices. Any such resale may be made directly to purchasers or to or through
brokers or dealers who may receive compensation in the form of commissions or
concessions from any such Broker-Dealer and/or the purchasers of any such
Exchange Securities. Any Broker-Dealer that resells Exchange Securities that
were received by it for its own account pursuant to the Exchange Offer and any
broker or dealer that participates in a distribution of such Exchange Securities
may be deemed to be an "underwriter" within the meaning of the Securities Act
and any profit of any such resale of Exchange Securities and any commissions or
concessions received by any such Persons may be deemed to be underwriting
compensation under the Securities Act. The Letter of Transmittal states that by
acknowledging that it will deliver and by delivering a prospectus, a
Broker-Dealer will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act.

            For a period of 180 days after the Expiration Date, the Company will
promptly send additional copies of this Prospectus and any amendment or
supplement to this Prospectus to any Broker-Dealer that requests such documents
in the Letter of Transmittal. The Company has agreed to pay all expenses
incident to the Exchange Offer (including the expenses of one counsel for the
holder of the Securities) other than commissions or concessions of any brokers
or dealers and will indemnify the holders of the Original Securities (including
any Broker-Dealers) against certain liabilities, including liabilities under the
Securities Act.

            [If applicable, add information required by Regulation S-K Items 507
and/or 508.]



                                       22
<PAGE>

                                                                       ANNEX D

RIDER A

                  CHECK HERE IF YOU ARE A BROKER-DEALER AND WISH TO RECEIVE 10
                  ADDITIONAL COPIES OF THE PROSPECTUS AND 10 COPIES OF ANY
                  AMENDMENTS OR SUPPLEMENTS THERETO.

                  Name:
                           --------------------------------------------
                  Address:
                           --------------------------------------------
                           --------------------------------------------


RIDER B

If the undersigned is not a Broker-Dealer, the undersigned represents that it
acquired the Exchange Securities in the ordinary course of its business, it is
not engaged in, and does not intend to engage in, a distribution of Exchange
Securities and it has not arrangements or understandings with any Person to
participate in a distribution of the Exchange Securities. If the undersigned is
a Broker-Dealer that will receive Exchange Securities for its own account in
exchange for Securities, it represents that the Original Securities to be
exchange for Exchange Securities were acquired by it as a result of
market-making activities or other trading activities and acknowledges that it
will deliver a prospectus in connection with any resale of such Exchange
Securities; however, by so acknowledging and by delivering a prospectus, the
undersigned will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act.


                                       23