Annenberg died of natural causes at Eisenhower Medical Center in Rancho Mirage, Calif., family spokeswoman Kathleen Hall Jamieson said. Her family was at her side, said Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania.
Annenberg was chairwoman and president of the Annenberg Foundation, which she headed since her husband's death in October 2002.
A prominent patron of the fine arts, Annenberg was a member of the board of trustees of the Philadelphia Museum of Art and a member of the acquisitions committee of the Metropolitan Museum of Art in New York. She also served on the Trustee's Council of The National Gallery of Art in Washington, D.C.
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Her husband served as ambassador to Britain under President Nixon. She brought in her own decorator to oversee a million-dollar refurbishment of the U.S. ambassador's residence in London.
A decade later, Leonore Annenberg was named U.S. chief of protocol, a position that carries the rank of ambassador, during President Ronald Reagan's first term.
In the job, she oversaw visits from foreign leaders and helped arrange Reagan's state visits abroad. She told The New York Times it was "the first paying job I ever had."
Walter Annenberg's father had started the family publishing empire, eventually acquiring the Philadelphia Inquirer. His son greatly expanded the businesses, adding the Philadelphia Daily News and branching out into magazines, including Seventeen and the hugely successful TV Guide. He also added radio and TV stations and amassed a multimillion-dollar art collection.
Her husband sold off his properties in the 1970s and '80s, bringing huge sums including a multibillion-dollar deal with Rupert Murdoch.
Walter Annenberg had a son and daughter with his first wife, Veronica, whom he divorced in 1950. His second wife, the former Leonore Cohn Rosenstiel, whom he married in 1951, had two daughters from a previous marriage.
He said it was as a favor to Leonore Annenberg that he made large bequests not only to his four grandchildren but also three stepgrandchildren -- "in recognition of the deep love that my wife, Leonore Annenberg, has for them and they for her."
She is survived by a sister, two daughters, one stepdaughter, seven grandchildren and eight great-grandchildren.