Exhibit 21 NIELSEN MEDIA RESEARCH, INC. Active Subsidiaries as of July 1, 1998 Jurisdiction of Name Incorporation % Ownership - ---- ------------- ----------- CZT/ACN Trademarks, L.L.C. Delaware 50% Nielsen Media Research Ltd. Nova Scotia 100% NMR Investing I, Inc. Delaware 100% NMR Licensing Associates, L.P. Delaware 78.53% Athenian Leasing Corporation Delaware 100%