<SEC-DOCUMENT>0001057352-17-000004-index.html : 20170222
<SEC-HEADER>0001057352-17-000004.hdr.sgml : 20170222
<ACCEPTANCE-DATETIME>20170222163724
ACCESSION NUMBER:		0001057352-17-000004
CONFORMED SUBMISSION TYPE:	8-K
PUBLIC DOCUMENT COUNT:		3
CONFORMED PERIOD OF REPORT:	20170222
ITEM INFORMATION:		Results of Operations and Financial Condition
ITEM INFORMATION:		Financial Statements and Exhibits
FILED AS OF DATE:		20170222
DATE AS OF CHANGE:		20170222

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COSTAR GROUP INC
		CENTRAL INDEX KEY:			0001057352
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-BUSINESS SERVICES, NEC [7389]
		IRS NUMBER:				522091509
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		8-K
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24531
		FILM NUMBER:		17628946

	BUSINESS ADDRESS:	
		STREET 1:		1331 L STREET NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20005
		BUSINESS PHONE:		2023466500

	MAIL ADDRESS:	
		STREET 1:		1331 L STREET NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20005
</SEC-HEADER>
<DOCUMENT>
<TYPE>8-K
<SEQUENCE>1
<FILENAME>form8-k_4q2016.htm
<DESCRIPTION>FORM 8-K
<TEXT>
Document 1 - file: form8-k_4q2016.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.1
<SEQUENCE>2
<FILENAME>a4q2016earningspressrelease.htm
<DESCRIPTION>2016 4Q PRESS RELEASE
<TEXT>
Document 2 - file: a4q2016earningspressrelease.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>3
<FILENAME>newcostargroupa11.jpg
<TEXT>
Document 3 - file: newcostargroupa11.jpg

</DOCUMENT>
</SEC-DOCUMENT>