Leonore “Lee” Annenberg, the former U.S. chief of protocol and president and chairman of The Annenberg Foundation, whose lifelong philanthropy entrusted billions of dollars to institutions around the country, died today of natural causes at Eisenhower Medical Center in Rancho Mirage, Calif. She was 91.

Together with her late husband, publisher and ambassador Walter H. Annenberg, Lee Annenberg was among the strongest supporters of USC. Since 1951, the Annenberg family and Annenberg Foundation have given $288.6 million to support programs in communication and journalism at USC.

The USC Annenberg School for Communication, along with its sister school at the University of Pennsylvania, are two of the many educational institutions across the country that bear the Annenberg name.

“A university can only become world-class with the help of world-class people,” said USC President Steven B. Sample. “Lee Annenberg is one of those people. She dedicated her entire life to improving the human condition through education and the arts.

“Thanks to Lee and her family, USC’s programs in communication are the strongest of any in the nation. Her unstinting generosity is matched by her wisdom, her foresight, her high ideals, her character and her warmth.”

Ernest J. Wilson III, dean of the USC Annenberg School for Communication, said: “Mrs. Annenberg is an icon and her engagement with the power of communication to improve humanity truly has changed the world.

“Her remarkable philanthropy has enhanced the effectiveness of public education, brought artistic treasures to wider audiences and furthered the impact of communication through two great schools that bear the family’s name. Her spirit and dedication are reflected in the work of this school, its faculty and its students every day.”

A graduate of Stanford University, Lee Annenberg was appointed U.S. chief of protocol by President Ronald Reagan, bringing her signature style to the administration’s diplomatic efforts. When Walter Annenberg was appointed ambassador to the Court of St. James’s, Lee Annenberg supervised the renovation of the embassy residence in London and founded the American Friends of Covent Garden. She remained a political fixture after leaving the administration in 1982, hosting royalty and heads of state at the family’s Sunnylands estate near Rancho Mirage.

She also turned her attention to philanthropy, promoting cultural appreciation, education and the arts. With the founding of The Annenberg Foundation in 1989, the Annenbergs soon became known as one of most generous couples in the country, disbursing nearly $3 billion in grants for education, arts and the humanities through the foundation alone. In 2001, she was awarded the Andrew Carnegie Medal of Philanthropy in recognition of the impact of her giving.

“Lee defined the word gracious, and her life and charities were a work of art,” said Geoffrey Cowan, USC University Professor, USC Annenberg School dean emeritus and holder of the Annenberg Family Chair in Communication Leadership. “All who visit Winfield House, the ambassador’s residence in London, are overcome by her sense of taste and style. Yet she was also exceptionally smart and had a will of steel. I am grateful for all that she has done for USC, and we will all miss her deeply. But her golden glow will live on through her family, her friends and her exceptional legacy of good deeds.”

Lee Annenberg has been instrumental in the growth of museums and nonprofit organizations around the country. She served on the boards of some of the country’s most influential institutions of the arts and humanities, including the University of Pennsylvania, the Metropolitan Museum of Art, the Philadelphia Museum of Art, the Pennsylvania Academy of Fine Arts, the National Gallery of Art, the Metropolitan Opera, the Los Angeles Music Center, the Philadelphia Orchestra Association and the Richard Nixon Library and Birthplace Foundation.

Among her many international honors and accolades are the Cavaliere Dell’Ordine “Al Merito Della Republica Italiana,” the Grand Officio Order of Orange-Nassau from the Netherlands, the National Medal of Arts from the National Endowment of the Arts, the Pat Nixon Ambassador of Goodwill Award, the Philadelphia Award and honorary doctorates from six colleges and universities.