Exhibit 5.1

                         [LONG ALDRIDGE & NORMAN LLP]

                              September 17, 2001

AGL Resources Inc.
817 West Peachtree Street, N.W.
Atlanta, Georgia  30308

     Re:  Registration Statement on Form S-3 of AGL Resources Inc., AGL Capital
          Corporation and AGL Capital Trust III

Ladies and Gentlemen:

     We have acted as counsel to AGL Resources Inc., a Georgia corporation ("AGL
Resources"), in connection with a Registration Statement on Form S-3 (the
"Registration Statement") which is being filed with the Securities and Exchange
Commission (the "Commission"), by AGL Resources, AGL Capital Corporation ("AGL
Capital") and AGL Capital Trust III (the "Trust").  Pursuant to the Registration
Statement, AGL Resources, AGL Capital and the Trust intend to register under the
Securities Act of 1933, as amended, up to $750,000,000 aggregate offering price
of (1) one or more series of debt securities, which may be issued by AGL Capital
(the "Debt Securities"), pursuant to an Indenture dated as of February 20, 2001
by and among AGL Resources, AGL Capital and The Bank of New York, as trustee
(the "Debt Securities Indenture"), (2) Common Stock, which may be issued by AGL
Resources, (3) Trust Preferred Securities, which may be issued by the Trust
pursuant to an Amended and Restated Trust Agreement, by and among AGL Capital,
as sponsor, The Bank of New York, as property trustee, The Bank of New York
(Delaware), as Delaware Trustee and the Administrative Trustees named therein
(the "Trust Agreement"), (4) _____% Junior Subordinated Deferrable Interest
Debentures, which may be issued by AGL Capital (the "Debentures"), pursuant to
an Indenture by and among AGL Resources, AGL Capital and The Bank of New York,
as trustee (the "Debenture Indenture"), (5) AGL Resources' Guarantee with
respect to the Trust Preferred Securities (the "Trust Preferred Securities
Guarantee") (6) AGL Resources' Guarantee with respect to the Debentures,
pursuant to the Trust Preferred Indenture (the "Debenture Guarantee"), and (7)
AGL Resources' Guarantee with respect to the Debt Securities, pursuant to the
Debt Securities Indenture (the "Debt Securities Guarantee" and collectively,
with the Trust Preferred Securities Guarantee and the Debenture Guarantee, the
"Guarantees").

     Our Opinions (as defined below) are furnished solely with regard to the
Registration Statement pursuant to Item 16 of Form S-3 and Item 601(b)(5) of
Regulation S-K, may be relied upon only in connection with the Registration
Statement and may not otherwise be used, quoted or referred to by or filed with
any other person or entity without our prior written permission.


AGL Resources Inc.
September 17, 2001
Page 2
____________________

     The only opinions rendered consist of the matters set forth in numbered
paragraphs 1 and 2 below (individually, an "Opinion," and collectively, our
"Opinions"), and no opinion is implied or to be inferred beyond such matters.
Additionally, our Opinions are based on and subject to the qualifications,
limitations and exceptions set forth in this letter.

     In rendering our Opinions, we have examined such agreements, documents,
instruments and records as we deemed necessary or appropriate under the
circumstances for us to express our Opinions hereinafter set forth, including:
(i) the Registration Statement; (ii) the Debt Securities Indenture; (iii) a form
of Debenture Indenture, (iv) a form of Trust Agreement, (v) a form of Trust
Preferred Securities Guarantee, (vi) the Articles of Incorporation and Bylaws of
AGL Resources, and (vii) minutes of proceedings of the Board of Directors of AGL
Resources.  In making all of our examinations, we assumed the competency and
legal capacity of all natural persons, the genuineness of all signatures, the
authenticity and completeness of all documents submitted to us as originals, the
conformity to the original documents of all documents submitted to us as copies
and the authenticity of the originals of such latter documents.  We also have
assumed the due execution and delivery of all documents by any persons or
entities other than AGL Resources where due execution and delivery by such
persons or entities is a prerequisite to the effectiveness of such documents.

     As to all questions of fact that are material to our Opinions, we have
assumed the factual accuracy of and relied upon the factual statements set forth
in a certificate of an officer of AGL Resources and certificates of various
public officials.  We have not independently verified or investigated, nor do we
assume any responsibility for, the factual accuracy or completeness of such
factual statements.

     The members of this firm are admitted to the bar of the State of Georgia
and are duly qualified to practice law in that state.  Our Opinions are limited
to the laws of the State of Georgia and applicable federal laws that are in
effect on the date of this letter and that, in our professional judgment, are
normally applicable to transactions of the type contemplated herein.  We express
no opinion with regard to any matter which may be governed by the laws of any
other jurisdiction.  We note that the governing law provision in the Trust
Preferred Indenture, Debt Securities Indenture and Trust Preferred Securities
Guarantee provides that such agreements are to be governed by the laws of the
State of New York.  We express no opinion as to whether any court of any
jurisdiction will give effect to the governing law provisions set forth in the
Trust Preferred Indenture, Debt Securities Indenture or Trust Preferred
Securities Guarantee but have assumed, with your permission, hypothetically for
purposes of our Opinions, that if AGL Resources is brought before a proper court
in the State of Georgia to enforce rights under the Trust Preferred Indenture,
Debt Securities Indenture or Trust Preferred Securities Guarantee, such court
will apply the substantive laws of the State of Georgia, notwithstanding the
governing law provisions contained in the Trust Preferred Indenture, Debt
Securities Indenture and Trust Preferred Securities Guarantee.  The Opinions
hereinafter set forth are based upon pertinent laws and facts in existence as of
the date hereof and we expressly disclaim any obligation to advise you of any
changes to such pertinent laws or facts that may hereafter come to our
attention.


AGL Resources Inc.
September 17, 2001
Page 3
____________________

     Based upon and subject to the foregoing, and assuming (a) that the Board of
Directors of AGL Resources or a committee thereof duly authorizes by proper
corporate action the terms and issuance of the Guarantees, (b) the qualification
of the Debenture Indenture, Trust Preferred Securities Guarantee and Trust
Agreement under the Trust Indenture Act of 1939, as amended, (c) the due
execution, authentication, issuance and delivery of the Debt Securities and
Debentures by AGL Capital Corporation upon payment of the consideration therefor
as provided in the applicable purchase, underwriting or similar agreements duly
approved by the requisite corporate action by AGL Resources and AGL Capital
Corporation and otherwise in accordance with the provisions of the Debt
Securities Indenture and Debenture Indenture, (d) the due authorization,
execution, issuance and delivery of the Trust Preferred Securities by the Trust,
(e) the due authorization, execution and delivery of the Debenture Indenture by
AGL Resources, AGL Capital and The Bank of New York, as trustee, and (f) the due
issuance of the Guarantees, we are of the Opinion that:

          (1) The Guarantees will constitute valid and binding obligations of
     AGL Resources, except that the enforceability of AGL Resources obligations
     may be limited by (a) bankruptcy, reorganization, insolvency, moratorium,
     fraudulent conveyance or transfer, or other laws or judicial decisions now
     or hereafter in effect relating to or affecting rights and remedies of
     creditors; (b) general principles of equity (regardless of whether
     considered in a proceeding at law or in equity) and matters of public
     policy; and (c) an implied covenant of good faith and fair dealing and
     potential unenforceability of certain contractual provisions.

          (2) Upon the issuance and sale of the Common Stock in accordance with
     resolutions to be adopted by AGL Resources and the receipt by AGL Resources
     of the full purchase price established therefor, the Common Stock will be
     duly authorized, validly issued, fully-paid and nonassessible.

     We hereby consent to the filing of this letter as an exhibit to the
Registration Statement and to the reference to our firm under the heading "Legal
Matters" set forth in the Prospectus forming a part of the Registration
Statement.

                                    Very truly yours,

                                    /s/ Long Aldridge & Norman LLP
                                    ------------------------------------------
                                    Long Aldridge & Norman LLP