Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

This Schedule 13G/A (this "Schedule 13G/A") is being filed on behalf of Praesidium Investment Management Company, LLC, a Delaware limited liability company (the "Management Company"), Peter Uddo and Kevin Oram (collectively, the "Reporting Persons"). Each of Mr. Uddo and Mr. Oram serve as a principal of the Management Company. The Management Company serves as an adviser to certain private investment funds and managed accounts (the "Funds"). This Schedule 13G/A relates to shares of Common Stock (the "Common Stock") of Comfort Systems USA, Inc., a Delaware corporation (the "Issuer") held by the Funds.


Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

CUSIP No. 199908104

SCHEDULE 13G/A

Page 8 of 10 Pages

Item 5. Ownership of Five Percent or Less of a Class

Not Applicable

Item 6. Ownership of More Than Five Percent on Behalf of Another Person

Not Applicable

Item 7. Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company or Control Person

Not Applicable

Item 8. Identification and Classification of Members of the Group

Not Applicable

Item 9. Notice of Dissolution of Group

Not Applicable

Item 10. Certification

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

Exhibits Exhibit 99.1

Joint Filing Agreement, dated February 12, 2013, by and among the Reporting Persons.

CUSIP No. 199908104

SCHEDULE 13G/A

Page 9 of 10 Pages

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: February 12, 2013

Praesidium Investment Management Company, LLC

By:	Peter Uddo
	Name:	Peter Uddo
	Title:	Managing Member


By:	Peter Uddo
	Name:	Peter Uddo



By:	Kevin Oram
	Name:	Kevin Oram

CUSIP No. 199908104

SCHEDULE 13G/A

Page 10 of 10 Pages

EXHIBIT 99.1

JOINT FILING AGREEMENT


1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Praesidium Investment Management Company, LLC 20-0302413
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a) o (b) o
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware, United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 2,833,702
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 2,995,330
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,995,330
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See Instructions)			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.03%
12	TYPE OF REPORTING PERSON (See Instructions) PN/ IA


1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Peter Uddo
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a) o (b) o
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 2,833,702
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 2,995,330
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,995,330
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See Instructions)			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.03%
12	TYPE OF REPORTING PERSON (See Instructions) IN


1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Kevin Oram
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a) o (b) o
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 2,833,702
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 2,995,330
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,995,330
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See Instructions)			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.03%
12	TYPE OF REPORTING PERSON (See Instructions) IN

(a)	¨	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)	¨	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)	¨	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)	¨	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)	x	An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)	¨	An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)	¨	A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)	¨	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)	¨	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)	¨	A non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J);

(k)	¨	A group, in accordance with §240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J), please specify the type of institution: