<SEC-DOCUMENT>0001057352-19-000049-index.html : 20190424
<SEC-HEADER>0001057352-19-000049.hdr.sgml : 20190424
<ACCEPTANCE-DATETIME>20190423184419
ACCESSION NUMBER:		0001057352-19-000049
CONFORMED SUBMISSION TYPE:	DEF 14A
PUBLIC DOCUMENT COUNT:		13
CONFORMED PERIOD OF REPORT:	20190605
FILED AS OF DATE:		20190424
DATE AS OF CHANGE:		20190423
EFFECTIVENESS DATE:		20190424

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:		DEF 14A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24531
		FILM NUMBER:		19762365

	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>DEF 14A
<SEQUENCE>1
<FILENAME>a2019proxystatement.htm
<DESCRIPTION>DEF 14A
<TEXT>
Document 1 - file: a2019proxystatement.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>2
<FILENAME>a3a01.jpg
<TEXT>
Document 2 - file: a3a01.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>3
<FILENAME>acsignaturea02.jpg
<TEXT>
Document 3 - file: acsignaturea02.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>4
<FILENAME>card1.jpg
<TEXT>
Document 4 - file: card1.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>5
<FILENAME>card2.jpg
<TEXT>
Document 5 - file: card2.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>6
<FILENAME>ebitdaa03.jpg
<TEXT>
Document 6 - file: ebitdaa03.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>7
<FILENAME>horizona01.jpg
<TEXT>
Document 7 - file: horizona01.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>8
<FILENAME>jcsignaturea02.jpg
<TEXT>
Document 8 - file: jcsignaturea02.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>9
<FILENAME>netincomea01.jpg
<TEXT>
Document 9 - file: netincomea01.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>10
<FILENAME>operatingrevenuea03.jpg
<TEXT>
Document 10 - file: operatingrevenuea03.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>11
<FILENAME>pie1.jpg
<TEXT>
Document 11 - file: pie1.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>12
<FILENAME>pie2v2.jpg
<TEXT>
Document 12 - file: pie2v2.jpg

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>13
<FILENAME>variablepaycharta01.jpg
<TEXT>
Document 13 - file: variablepaycharta01.jpg

</DOCUMENT>
</SEC-DOCUMENT>