8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of report (Date of earliest event reported): September 16, 2005

SOUTHWESTERN ENERGY COMPANY

(Exact name of registrant as specified in its charter)

Arkansas

(State or other jurisdiction of incorporation)

1-8246	71-0205415
(Commission File Number)	(IRS Employer Identification No.)
2350 N. Sam Houston Pkwy. E., Suite 300, Houston, Texas	77032
(Address of principal executive offices)	(Zip Code)

(281) 618-4700

(Registrant's telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Section 9. Financial Statements and Exhibits.

(d) Exhibits.

99.1 Opinion of Cleary Gottlieb Steen & Hamilton LLP.

99.2 Opinion of Jeffrey L Dangeau.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	SOUTHWESTERN ENERGY COMPANY
Dated: September 16, 2005	By:	/s/    GREG D. KERLEY
	Name:	Greg D. Kerley
	Title:	Executive Vice President and
		Chief Financial Officer

EXHIBIT INDEX

Exhibit No. Description

99.1 Opinion of Cleary Gottlieb Steen & Hamilton LLP.

99.2 Opinion of Jeffrey L Dangeau.

EX-99.1

[CLEARY GOTTLIEB STEEN & HAMILTON LLP letterhead]

Writer’s Direct Dial: (212) 225-2420

E-Mail: sshalen@cgsh.com

September 16, 2005

Southwestern Energy Company

2350 North Sam Houston Parkway East

Suite 300

Houston, Texas 77032

Ladies and Gentlemen:

We have acted as counsel to Southwestern Energy Company (the “Company”) in connection with the Registration Statement on Form S-3, Registration No. 333-126884 (the “Registration Statement”), filed on July 26, 2005 with the Securities and Exchange Commission (the “SEC”) pursuant to the Securities Act of 1933, as amended, and the proposed sale pursuant to a prospectus supplement dated September 14, 2005 to prospectus dated September 1, 2005 of shares of the Company’s common stock (the “Common Shares”).

We have participated in the preparation of the Registration Statement and have reviewed the originals or copies certified or otherwise identified to our satisfaction of all such corporate records of the Company and such other instruments and other certificates of public officials, officers and representatives of the Company and such other persons, and we have made such investigations of law, as we have deemed appropriate as a basis for the opinion expressed below.

In arriving at the opinion expressed below, we have assumed the authenticity of all documents submitted to us as originals and the conformity to the originals of all documents submitted to us as copies. In addition, we have assumed and have not verified the accuracy as to factual matters of each document we have reviewed.

Based on the foregoing, and subject to the further assumptions and qualifications set forth below, it is our opinion that the Common Shares have been duly authorized by all necessary corporate action of the Company, and upon issuance in accordance with the terms of the underwriting agreement dated September 14, 2005 will be validly issued, fully paid and nonassessable.

In giving the foregoing opinion we have relied without independent investigation, as to matters relating to the law of Arkansas, on the opinion dated the date hereof of Jeffrey L. Dangeau, General Counsel of Arkansas Western Gas Company, the Company’s wholly owned subsidiary, and our opinions are subject to all of the limitations and qualifications contained therein. Except insofar as we have relied on such opinion, the foregoing opinion is limited to the federal law of the United States of America and the law of the State of New York.

Southwestern Energy Company, p. 2

We hereby consent to the filing of this opinion with the SEC and to the use of our name under the caption "Legal Matters" in the Registration Statement and in the prospectus which forms a part of the Registration Statement and any supplement or supplements to such prospectus. By the giving of such consent, we do not admit that we are experts with respect to any part of the Registration Statement, or otherwise, within the meaning of the Rules and Regulations of the SEC.

Very truly yours,

CLEARY GOTTLIEB STEEN & HAMILTON LLP

By                   /s/ STEPHEN H. SHALEN       

Stephen H. Shalen, a partner

EX-99.2

[LETTERHEAD OF ARKANSAS WESTERN GAS COMPANY]

September 16, 2005

Cleary Gottlieb Steen & Hamilton LLP

One Liberty Plaza

New York, New York 10006

Ladies and Gentlemen:

I am General Counsel of Arkansas Western Gas Company, a subsidiary of Southwestern Energy Company (“Southwestern”), an Arkansas corporation, and as such have acted as the Company’s advisor in connection with the Registration Statement on Form S-3, Registration No. 333-126884 (the “Registration Statement”), filed on July 26, 2005 with the Securities and Exchange Commission (the “SEC”) pursuant to the Securities Act of 1933, as amended, and the proposed sale pursuant to a prospectus supplement dated September 14, 2005 to prospectus dated September 1, 2005 of shares of the Company’s common stock (the “Common Shares”).

In arriving at the opinions expressed below, I have examined and relied on the originals or copies certified or otherwise identified to my satisfaction of all such corporate records of Southwestern and such other instruments and other certificates of public officials, officers and representatives of Southwestern and such other persons, and I have made such investigations of law, as I have deemed appropriate as a basis for the opinions expressed below. In rendering the opinions expressed below, I have assumed and not verified that signatures on all documents which I have examined are genuine.

Based upon the foregoing and subject to the further assumptions and qualifications set forth below, I am of the opinion that the Common Shares have been duly authorized by all necessary corporate action of Southwestern, and upon issuance in accordance with the terms of the underwriting agreement dated September 14, 2005 will be validly issued, fully paid and nonassessable.

                In rendering this opinion, I express no opinion other than as to the laws of the State of Arkansas.

Cleary Gottlieb Steen & Hamilton LLP, p.2

                I hereby consent to the filing of this opinion with the SEC and the reference to me under the heading “Legal Matters” in the Registration Statement and in the Prospectus which forms a part of the Registration Statement and any supplement or supplements to such Prospectus. As of September 16, 2005, I beneficially owned approximately 54,040 shares of the Company’s common stock and options to purchase approximately 53,224 shares of common stock. By giving such consent, I do not admit that I am an expert with respect to any part of the Registration Statement, including this opinion as an exhibit, or otherwise, within the meaning of the term “Expert” as used in the Rules and Regulations of the SEC.

Very truly yours,

/s/ Jeffrey L. Dangeau

Jeffrey L. Dangeau

General Counsel

Arkansas Western Gas Company