<SEC-DOCUMENT>0001057352-15-000040-index.html : 20150429
<SEC-HEADER>0001057352-15-000040.hdr.sgml : 20150429
<ACCEPTANCE-DATETIME>20150429172049
ACCESSION NUMBER:		0001057352-15-000040
CONFORMED SUBMISSION TYPE:	8-K
PUBLIC DOCUMENT COUNT:		5
CONFORMED PERIOD OF REPORT:	20150427
ITEM INFORMATION:		Entry into a Material Definitive Agreement
ITEM INFORMATION:		Results of Operations and Financial Condition
ITEM INFORMATION:		Financial Statements and Exhibits
FILED AS OF DATE:		20150429
DATE AS OF CHANGE:		20150429

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:		15814069

	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_1q.htm
<DESCRIPTION>8-K
<TEXT>
Document 1 - file: form8-k_1q.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-2.1
<SEQUENCE>2
<FILENAME>ex2_1mergeragreementconfor.htm
<DESCRIPTION>EXHIBIT 2.1
<TEXT>
Document 2 - file: ex2_1mergeragreementconfor.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-10.1
<SEQUENCE>3
<FILENAME>ex10_1formofvotingagreement.htm
<DESCRIPTION>EXHIBIT 10.1
<TEXT>
Document 3 - file: ex10_1formofvotingagreement.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.1
<SEQUENCE>4
<FILENAME>a1q2015earningspressrelease.htm
<DESCRIPTION>EXHIBIT 99.1
<TEXT>
Document 4 - file: a1q2015earningspressrelease.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>5
<FILENAME>newcostargroupa06.jpg
<TEXT>
Document 5 - file: newcostargroupa06.jpg

</DOCUMENT>
</SEC-DOCUMENT>