Financial terms of the deal were not disclosed.
Monroe Mendelsohn is being renamed Ipsos Mendelsohn. Its clients include Dow Jones & Co., Havas, Publicis, Time Warner and WPP Group.
Separately, Ipsos appointed Mark Kostelec senior VP-sales and marketing for Ipsos’ U.S. Media, Content and Technology division. Kostelec was previously international VP of Newsweek.