0001057352-08-000097 4 1 20081212 20081215 20081215 Stanfill John L 0001438487 4 34 000-24531 081250408 301-215-8300 C/O COSTAR GROUP, INC. 2 BETHESDA METRO CENTER, 10TH FLOOR BETHESDA MD 20714 COSTAR GROUP INC 0001057352 7389 522091509 1231 2 BETHESDA METRO CENTER 10TH FLOOR BETHESDA MD 20814 3012158300 2 BETHESDA METRO CENTER 10TH FLOOR BETHESDA MD 20814 4 1 edgar.xml PRIMARY DOCUMENT