Decima cost Harris $21.3m in cash. It will provide the firm with access to the Canadian market, through offices in Montreal, Toronto and Vancouver, and headquarters based in Ottawa.
Harris hopes that the acquisition will prove profitable, and said it was impressed with Decima's trading results last year, when it generated $26.2m in revenue. It also has an extensive online survey panel, consisting of 140,000 members.
Bruce Anderson, CEO of Decima Research, said: "This new union will allow us to utilise the technological muscle and extensive research solutions of Harris Interactive to better serve our clients."
Harris has paid $2.8m for MarketShare, an Asia-Pacific market research firm with joint headquarters in Hong Kong and Singapore. It has worked with the firm on global and regional accounts since 2004.
Gregory Novak, president and CEO of Harris Interactive said: "Adding the strengths of these firms to the Harris Interactive enterprise will improve our global service offering and provide increased access into two fast-growing regions that represent about a $4bn market opportunity."