UNITED STATES 
                  SECURITIES AND EXCHANGE COMMISSION 
                        Washington, D.C. 20549 
                                    
                                    
                             SCHEDULE 13G 
                                    
               Under the Securities Exchange Act of 1934 
                                    
                                    
                          (Amendment No. 7)* 
                                    
                                    
                            Costar Group, Inc. 
                             (Name of Issuer) 
                                      
                               Common Stock 
                      (Title of Class of Securities) 
                                      
                                22160N109 
                              (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). 
                                    


















CUSIP: 22160N109                                                Page 1 of 7 

                                    
 1   NAMES OF REPORTING PERSONS 
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) 
     Capital Group International, Inc. 
     95-4154357 
      
 2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE          
     INSTRUCTIONS)                                                 (a)     
                                                                      
                                                                    (b)     
 3   SEC USE ONLY 
      
      
 4   CITIZENSHIP OR PLACE OF ORGANIZATION 
      
     California 

             5   SOLE VOTING POWER 
                   
                  24,900 

       
             6   SHARED VOTING POWER 
 NUMBER OF         
   SHARES         NONE 
BENEFICIALL        
 Y OWNED BY 
             7   SOLE DISPOSITIVE POWER 
    EACH           
 REPORTING        47,750 
   PERSON 
   WITH: 
             8   SHARED DISPOSITIVE POWER 
                   
                  NONE 
                   
 9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 
      
     47,750     Beneficial ownership disclaimed pursuant to Rule 13d-4  



 10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES 
     (SEE INSTRUCTIONS) 
      
      
 11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 
      
     0.3% 

 12  TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) 
      
     HC   







CUSIP: 22160N109                                                Page 2 of 7 
 
 
 

                                    
 1   NAMES OF REPORTING PERSONS 
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) 
     Capital Guardian Trust Company 
     95-2553868 
      
 2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE          
     INSTRUCTIONS)                                                 (a)     
                                                                      
                                                                    (b)     
 3   SEC USE ONLY 
      
      
 4   CITIZENSHIP OR PLACE OF ORGANIZATION 
      
     California 

             5   SOLE VOTING POWER 
                   
                  24,900 

       
             6   SHARED VOTING POWER 
 NUMBER OF         
   SHARES         NONE 
BENEFICIALL        
 Y OWNED BY 
             7   SOLE DISPOSITIVE POWER 
    EACH           
 REPORTING        47,750 
   PERSON 
   WITH: 
             8   SHARED DISPOSITIVE POWER 
                   
                  NONE 
                   
 9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 
      
     47,750     Beneficial ownership disclaimed pursuant to Rule 13d-4  



 10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES 
     (SEE INSTRUCTIONS) 
      
      
 11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 
      
     0.3% 

 12  TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) 
      
     IA  BK 

 




CUSIP: 22160N109                                                Page 3 of 7 
 
 
 

                  SECURITIES AND EXCHANGE COMMISSION 
                         Washington, DC 20549 
                                    
                             Schedule 13G 
               Under the Securities Exchange Act of 1934 
                                    
                                    
Amendment No. 7 
 
Item 1(a)     Name of Issuer: 
       Costar Group, Inc. 
 
Item 1(b)     Address of Issuer's Principal Executive Offices: 
       2 Bethesda Metro Center, 10th Floor 
       Bethesda, MD  20814 
        
Item 2(a)     Name of Person(s) Filing: 
       Capital Group International, Inc. and Capital Guardian Trust 
       Company 
        
Item 2(b)     Address of Principal Business Office or, if none, 
       Residence: 
       11100 Santa Monica Blvd. 
       Los Angeles, CA  90025 
        
Item 2(c)     Citizenship:   N/A 
        
Item 2(d)     Title of Class of Securities: 
       Common Stock 
        
Item 2(e)     CUSIP Number: 
       22160N109 
        
Item 3     If this statement is filed pursuant to sections 240.13d-1(b) 
       or 240.13d-2(b) or (c), check whether the person filing is a:  
       (d)     [X]     Investment company registered under section 8 
            of the Investment Company Act of 1940 (15 U.S.C. 80a-8). 
       (g)     [X]     A parent holding company or control person in 
            accordance with section 240.13d-1(b)(1)(ii)(G). 
        
Item 4     Ownership 
        
       Provide the following information regarding the aggregate 
       number and percentage of the class of securities of the issuer 
       identified in Item 1. 
        
       See pages 2 and 3 
        
       (a)    Amount beneficially owned: 
       (b)    Percent of class: 
       (c)    Number of shares as to which the person has: 
       (i)    Sole power to vote or to direct the vote: 
       (ii)   Shared power to vote or to direct the vote: 
       (iii)  Sole power to dispose or to direct the disposition of: 
       (iv)   Shared power to dispose or to direct the disposition of: 
        


CUSIP: 22160N109                                                Page 4 of 7 
 
 
 

                                    
       Capital Group International, Inc. ("CGII") is the parent 
       holding company of a group of investment management companies 
       that hold investment power and, in some cases, voting power 
       over the securities reported in this Schedule 13G.  The 
       investment management companies, which include a "bank" as 
       defined in Section 3(a)(6) of the Securities Exchange Act of 
       1934 (the "Act") and several investment advisers registered 
       under Section 203 of the Investment Advisers Act of 1940, 
       provide investment advisory and management services for their 
       respective clients which include registered investment 
       companies and institutional accounts.  CGII does not have 
       investment power or voting power over any of the securities 
       reported herein.  However, by virtue of Rule 13d-3 under the 
       Act, CGII may be deemed to "beneficially own" 47,750 shares or 
       0.3% of the 18,298,000 shares of  Common Stock believed to be 
       outstanding. 
        
       Capital Guardian Trust Company, a bank as defined in Section 
       3(a)(6) of the Act is deemed to be the beneficial owner of 
       47,750 shares or 0.3% of the 18,298,000 shares of Common Stock 
       believed to be outstanding as a result of its serving as the 
       investment manager of various institutional accounts. 
        
Item 5     Ownership of Five Percent or Less of a Class.  If this 
       statement is being filed to report the fact that as of the date 
       hereof the reporting person has ceased to be the beneficial 
       owner of more than five percent of the class of securities, 
       check the following: [X] 
        
Item 6     Ownership of More than Five Percent on Behalf of Another 
       Person: N/A 
        
Item 7     Identification and Classification of the Subsidiary Which 
       Acquired the Security Being Reported on By the Parent Holding 
       Company or Control Person. 
        
       1. Capital Guardian Trust Company is a bank as defined in 
          Section 3(a)(6) of the Act and an investment adviser 
          registered under Section 203 of the Investment Adviser Act of 
          1940, and a wholly owned subsidiary of Capital Group 
          International, Inc. 
        
Item 8     Identification and Classification of Members of the Group:  
       N/A 
        
Item 9     Notice of Dissolution of Group:  N/A 
        
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. 
        

CUSIP: 22160N109                                                Page 5 of 7 
 

                                    
     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:          February 11, 2005 
                        
        Signature:     *David I. Fisher 
        Name/Title:    David I. Fisher, Chairman 
                       Capital Group International, Inc. 
 
        Date:          February 11, 2005 
                        
        Signature:     *David I. Fisher 
        Name/Title:    David I. Fisher, Chairman 
                       Capital Guardian Trust Company 
 
        
        
        *By    /s/ Kenneth R. Gorvetzian 
               Kenneth R. Gorvetzian 
               Attorney-in-fact 
        
               Signed pursuant to a Power of Attorney dated January 30, 
               2003 included as an Exhibit to Schedule 13G filed with 
               the Securities and Exchange Commission by Capital Group 
               International, Inc. on February 10, 2003 with respect to 
               Acclaim Entertainment Inc. 


























CUSIP: 22160N109                                                Page 6 of 7 
 

                               AGREEMENT 
                                    
                            Los Angeles, CA 
                           February 11, 2005 
 
  Capital Group International, Inc. ("CGII") and Capital Guardian 
Trust Company ("CGTC") hereby agree to file a joint statement on 
Schedule 13G under the Securities Exchange Act of 1934 (the "Act") in 
connection with their beneficial ownership of Common Stock issued by 
Costar Group, Inc. 
   
  CGII and CGTC state that they are each entitled to individually use 
Schedule 13G pursuant to Rule 13d-1(c) of the Act. 
   
  CGII and CGTC are each responsible for the timely filing of the 
statement and any amendments thereto, and for the completeness and 
accuracy of the information concerning each of them contained therein 
but are not responsible for the completeness or accuracy of the 
information concerning the others. 
   
   
   
                 CAPITAL GROUP INTERNATIONAL, INC. 
                  
                 BY:              *David I. Fisher 
                                  David I. Fisher, Chairman 
                                   Capital Group International, 
                                   Inc. 
 
 
                 CAPITAL GUARDIAN TRUST COMPANY 
                  
                 BY:              *David I. Fisher 
                                  David I. Fisher, Chairman 
                                   Capital Guardian Trust Company 
 
 
*By  /s/ Kenneth R. Gorvetzian 
     Kenneth R. Gorvetzian 
     Attorney-in-fact 
      
     Signed pursuant to a Power of Attorney dated January 30, 2003 
     included as an Exhibit to Schedule 13G filed with the Securities 
     and Exchange Commission by Capital Group International, Inc. on 
     February 10, 2003 with respect to Acclaim Entertainment Inc. 
      















CUSIP: 22160N109                                                Page 7 of 7