The new agency will specialise in social media planning and buying, community creation and management, plus development, design and build of social media campaigns and platforms.
It will be run by Steve Parker, who joins the agency from the global PR company Cohn & Wolfe, and Patricia McDonald, the head of digital strategy at CHI.
Parker has worked in PR for 14 years, overseeing campaigns for John Lewis, Universal Pictures and Dell. McDonald joined CHI in February last year, having spent 11 years at Bartle Bogle Hegarty, latterly as the global business director on Levi's.
The Social Practice will work closely with a number of CHI's clients, including TalkTalk. It will also form strategic alliances with other WPP companies, such as Buddy Media and Visible Technologies, to help boost its product offering.
Parker says: "The Social Practice offers brands an objective blend of the planning, creative and digital services they need to thrive in the age of the networked consumer."