0000950133-00-001739 DEF 14A 1 20000621 20000428 COSTAR GROUP INC 0001057352 7374 521543845 DE 1231 DEF 14A 34 000-24531 613226 7475 WISCONSIN AVE. SUITE 600 BETHESDA MD 20814 3012158300 4600 EAST WEST HWY BETHESDA MD 20814 DEF 14A 1 000095013300001739-001-seq1-def-14a.txt DEF 14A PROXY STATEMENT