The 58-year-old Penn was named CEO in 2005 and will take a role as corporate VP of strategic and special projects at Microsoft, where he has advised top brass since 1998.
“He has a full sense of the firm’s culture, operations, and great potential, and I feel confident about the future of Burson-Marsteller as I leave it in Don’s capable hands,” said Penn, who juggled the dual roles of B-M CEO and chief strategist for Hillary Clinton's 2008 presidential bid.
Baer was communications director for President Bill Clinton from 1994-98 before moving into the private sector as senior VP for strategy and development of Discovery Communications.
He started out as a media lawyer in New York and moved into journalism, including stints at U.S. News and World Report and The American Lawyer.
WPP CEO Martin Sorrell said in a statement that he is confident the firm’s “track record of success” and reputation in the industry will continue under Baer.
B-M founding chairman Harold Burson called the move a “master stroke,” calling Baer one of the best PR professionals he has ever encountered. Added Burson: “Mark Penn has left a strong foundation on which to build. My colleagues and I wish him well in his new responsibility at Microsoft.”
Microsoft said Penn, based in D.C. but spending “substantial time” in Redmond, Wash., will focus on key consumer initiatives and lead a small interdisciplinary team under CEO Steve Ballmer.
The company said he will continue to write about consumer, demographic and social trends but will not be involved in public policy issues for the tech giant.