Exhibit 21.1

Name of Subsidiary		Jurisdiction of Incorporation
comScore Brand Awareness, L.L.C.		Delaware, U.S.A.
Creative Knowledge, Inc.		Delaware, U.S.A.
Gatesmith Enterprises, Inc.		Delaware, U.S.A.
Marketscore, Inc.		Delaware, U.S.A.
TMRG, Inc.		Delaware, U.S.A.
VoiceFive Networks, Inc.		Delaware, U.S.A.
comScore Europe, Inc.		Delaware, U.S.A.
comScore Canada, Inc.		Ontario, Canada
comScore Japan, K.K.		Japan
comScore Asia Limited		Hong Kong
M:Metrics, Inc.		Delaware, U.S.A
M:Metrics Limited		United Kingdom