Terms of the deal were not disclosed.
Interpublic said the company will operate as an independent, stand-alone business within the company's Partnership division.
Richard Kostyra, Media First's founder, president and CEO, will continue at the helm of the media company, and will report to Interpublic Vice Chairman David Bell, who oversees the Partnership.
Media First was founded in December 1992 by Mr. Kostyra. According to Interpublic, Media First managed over $330 million of media expenditures in 2001. The company's clients include Burger King Corp. and Northwest Airlines; services offered include media planning, buying, consulting, barter, promotion programs, online and international.