Pittman, currently co-chief operating officer with Richard Parsons at AOL Time Warner, was in charge of AOL's operations before its merger with Time Warner.
He adds the responsibilities to his role as chief operating officer, which he takes on solely when Parsons takes over as CEO after Gerald Levin retires in May.
Pittman's appointment comes at a crucial time for AOL, as subscriber growth slows and it attempts to encourage its 30m customers to upgrade to high-speed internet connections.
Parsons said: "Nobody understands AOL's operations and potential better than Bob Pittman and no one is better qualified to manage this business. Bob is taking on this role at a time of both opportunity and challenge. The challenge facing us at AOL is to improve the performance of its advertising business in the current slowdown by building on AOL's unique competitive position and capabilities."
Meanwhile, Schuler, who became AOL CEO and chairman in January 2001, is to lead a new division called Digital Services Development, developing interactive products for the company.
Schuler joined AOL in 1995, when Medior, the company he founded in 1989, was acquired by the ISP. Before becoming CEO and chairman of AOL, he was president of interactive services.
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