UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                               (Amendment No. 1 )*
                               -------------------

                                  Watsco, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    942622200
                  ---------------------------------------------
                                 (CUSIP Number)

                                December 31, 2004
             -------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


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

                                [x] Rule 13d-1(b)
                                [ ] Rule 13d-1(c)
                                [ ] Rule 13d-1(d)

*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 the
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).

                               Page 1 of 10 pages



                                       13G

CUSIP No.         942622200
                  ------------------------


--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

            Columbia Wanger Asset Management, L.P.  04-3519872
--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

            Not Applicable                                              (a)  [ ]

                                                                        (b)  [ ]
--------------------------------------------------------------------------------
  3     SEC USE ONLY
--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware

--------------------------------------------------------------------------------
                       5    SOLE VOTING POWER
     NUMBER OF
                                None
       SHARES         ----- ----------------------------------------------------
                       6    SHARED VOTING POWER                                 
    BENEFICIALLY                                                                
                                2,556,700                                       
      OWNED BY                                                                  
                      ----- ----------------------------------------------------
        EACH           7    SOLE DISPOSITIVE POWER                              
                                                                                
     REPORTING                  None                                            
                                                                                
    PERSON WITH       ----- ----------------------------------------------------
                                                                                
                       8    SHARED DISPOSITIVE POWER                            
                                                                                
                                2,556,700                                       

--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            2,556,700

--------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable                                                    [ ]

--------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           11.1%


--------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON*

           IA

--------------------------------------------------------------------------------

                               Page 2 of 10 pages





                                       13G

CUSIP No.         942622200
                  ------------------------


------- ------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

            WAM Acquisition GP, Inc.

--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

            Not Applicable                                              (a)  [ ]

                                                                        (b)  [ ]
--------------------------------------------------------------------------------
  3     SEC USE ONLY
--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware

--------------------------------------------------------------------------------
                       5    SOLE VOTING POWER
     NUMBER OF
                                None
       SHARES         ----- ----------------------------------------------------
                       6    SHARED VOTING POWER                                 
    BENEFICIALLY                                                                
                                2,556,700                                       
      OWNED BY                                                                  
                      ----- ----------------------------------------------------
        EACH           7    SOLE DISPOSITIVE POWER                              
                                                                                
     REPORTING                  None                                            
                                                                                
    PERSON WITH       ----- ----------------------------------------------------
                       8    SHARED DISPOSITIVE POWER                            
                                                                                
                                2,556,700                                       
                      
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            2,556,700

--------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable                                                    [ ]

--------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           11.1 %

--------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON*

           CO

--------------------------------------------------------------------------------


                               Page 3 of 10 pages





                                                            13G

CUSIP No.         942622200
                  ------------------------


--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

            Columbia Acorn Trust

--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

            Not Applicable                                              (a)  [ ]

                                                                        (b)  [ ]
--------------------------------------------------------------------------------
  3     SEC USE ONLY
--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

            Massachusetts

--------------------------------------------------------------------------------
                       5    SOLE VOTING POWER
     NUMBER OF
                                None
       SHARES         ----- ----------------------------------------------------
                       6    SHARED VOTING POWER                                 
    BENEFICIALLY                                                                
                                2,276,000                                       
      OWNED BY                                                                  
                      ----- ----------------------------------------------------
        EACH           7    SOLE DISPOSITIVE POWER                              
                                                                                
     REPORTING                  None                                            
                                                                                
    PERSON WITH       ----- ----------------------------------------------------
                       8    SHARED DISPOSITIVE POWER                            
                                                                                
                                2,276,000                                       
                                                                                
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            2,276,000

--------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable                                                    [ ]

--------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           9.9%

--------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON*

           IV

--------------------------------------------------------------------------------

                               Page 4 of 10 Pages




Item 1(a)                  Name of Issuer:

                                    Watsco, Inc.


Item 1(b)                  Address of Issuer's Principal Executive Offices:

                                    2665 South Bayshore Drive
                                    Suite 901
                                    Coconut Grove, FL  33133


Item 2(a)                  Name of Person Filing:

                                    Columbia Wanger Asset Management, L.P.
                                       ("WAM")
                                    WAM Acquisition GP, Inc., the general 
                                       partner of WAM ("WAM GP")
                                    Columbia Acorn Trust ("Acorn")


Item 2(b)                  Address of Principal Business Office:

                                    WAM, WAM GP, and Acorn are located at:
                                    227 West Monroe Street, Suite 3000
                                    Chicago, Illinois  60606


Item 2(c)                  Citizenship:

                                    WAM is a Delaware limited partnership; WAM
                                    GP is a Delaware corporation; Acorn is a
                                    Massachusetts business trust.

Item 2(d)                  Title of Class of Securities:

                                    Common Stock

Item 2(e)                  CUSIP Number:

                                    942622200

Item 3                     Type of Person:

                                    (d)     Acorn is an Investment Company under
                                            section 8 of the Investment
                                            Company Act.

                                    (e)     WAM is an Investment Adviser
                                            registered under section 203 of the
                                            Investment Advisers Act of 1940; WAM
                                            GP is the General Partner of the
                                            Investment Adviser.


                               Page 5 of 10 Pages






Item 4                     Ownership (at December 31, 2004):

                                    (a)     Amount owned "beneficially" within
                                            the meaning of rule 13d-3:

                                            2,556,700

                                    (b)     Percent of class:

                                            11.1% (based on 23,103,869 shares 
                                            outstanding as of October 29,2004)

                                    (c)     Number of shares as to which such
                                            person has:

                                                  (i)  sole power to vote or to
                                                       direct the vote: none
                                                 (ii)  shared power to vote or 
                                                       to direct the vote:
                                                       2,556,700
                                                (iii)  sole power to dispose or
                                                       to direct the disposition
                                                       of: none
                                                 (iv)  shared power to dispose
                                                       or to direct disposition
                                                       of: 2,556,700

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:

                                    The shares reported herein have been
                                    acquired on behalf of discretionary clients
                                    of WAM, including Acorn. Persons other than
                                    WAM and WAM GP are entitled to receive all
                                    dividends from, and proceeds from the sale
                                    of, those shares. Acorn is the only such
                                    person known to be entitled to all dividends
                                    from, and all proceeds from the sale of,
                                    shares reported herein to the extent of more
                                    than 5% of the class.

Item 7                     Identification and Classification of the Subsidiary
                           Which Acquired the Security Being Reported on by the
                           Parent Holding Company:

                                    Not Applicable

Item 8                     Identification and Classification of Members of 
                           the Group:

                                    Not Applicable

Item 9                     Notice of Dissolution of Group:

                                    Not Applicable


                               Page 6 of 10 Pages



Item 10                    Certification:

                                    By signing below I certify that, to the best
                           of my knowledge and belief, the securities referred
                           to above were acquired and are held in the ordinary
                           course of business and 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.

                               Page 7 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.

Date: January 10, 2005


                           The undersigned corporation, on the date above
                           written, agrees and consents to the joint filing on
                           its behalf of this Schedule 13G in connection with
                           its beneficial ownership of the security reported
                           herein.

                                  WAM Acquisition GP, Inc.
                                      for itself and as general partner of
                                      COLUMBIA WANGER ASSET MANAGEMENT, L.P.



                                  By:  /s/ Bruce H. Lauer                       
                                       -----------------------------------------
                                             Bruce H. Lauer
                                             Senior Vice President and Secretary

                           The undersigned trust, on the date above written,
                           agrees and consents to the joint filing on its behalf
                           of this Schedule 13G in connection with its
                           beneficial ownership of the security reported herein.

                                  COLUMBIA ACORN TRUST



                                  By:  /s/ Bruce H. Lauer                       
                                       -----------------------------------------
                                             Bruce H. Lauer
                                             Vice President, Treasurer and
                                             Secretary

                               Page 8 of 10 Pages




                                  Exhibit Index

Exhibit 1                              Joint Filing Agreement dated as of 
                                       January 10, 2005 by and among Columbia
                                       Wanger Asset Management, L.P., WAM
                                       Acquisition  GP, Inc. and Columbia Acorn
                                       Trust.


                               Page 9 of 10 Pages




                                                                       EXHIBIT 1

                             JOINT FILING AGREEMENT

         The undersigned hereby agree to the joint filing of the Schedule 13G to
which this Agreement is attached.

                           Dated:  January 10, 2005


                                  WAM Acquisition GP, Inc.
                                      for itself and as general partner of
                                      COLUMBIA WANGER ASSET MANAGEMENT, L.P.



                                  By:  /s/ Bruce H. Lauer                       
                                       -----------------------------------------
                                             Bruce H. Lauer
                                             Senior Vice President and Secretary




                                  COLUMBIA ACORN TRUST



                                  By:  /s/ Bruce H. Lauer                       
                                       -----------------------------------------
                                             Bruce H. Lauer
                                             Vice President, Treasurer and
                                             Secretary

                               Page 10 of 10 Pages