When the Metropolitan Museum of Art throws its annual Costume Institute gala on Dec. 7, its only anchors in the past will be the theme, Cubism and fashion, and the event's glamorous history-this will be the 50th anniversary of what was once dubbed the party of the year. Save for some of the venerable partygoers, there will be no remnants of the Old Social Guard who long dominated the direction of the event.

Each year, the troika chosen to chair the event is interpreted as some indication of Manhattan's social climate. When, in 1995, socialite Patricia Buckley handed over the reins of the costume gala to Vogue editor Anna Wintour and socialites Annette de la Renta, the wife of the fashion designer, and Clarissa Alcock Bronfman, the wife of Edgar Bronfman Jr., chief executive of Seagram Company Ltd., the perception was that the city's meritocracy had succeeded its aristocracy.

But this year's trio of fashion designer Miuccia Prada, socialite Pia Getty (the oldest daughter of duty-free magnate Robert Miller) and art collector Paula Cussi, sends another message entirely: that power in the city increasingly has little to do with Manhattan at all.

New York is a metropolis of outsiders, to be sure, but outsiders who've chosen the city as their home. Ms. Wintour and also her rival, Harper's Bazaar editor Liz Tilberis, who co-chaired the event in 1996, are both British expatriates who at least maintain permanent addresses in Manhattan. Of this year's triumvirate, it can be said that only Ms. Getty makes her home in New York. Ms. Prada lives in Milan, and Ms. Cussi lives primarily in Mexico City, according to an associate.

Harold Holzer, vice president for communications at the Met, told The Transom that too much should not be read into the far-flung home bases of the chairmen.

"This is an international event. It's not bound by any geographical constraints," said Mr. Holzer. "This may be yet another recognition of its global stature."

Ms. Prada and Ms. Getty are not unusual choices. For better or worse, they represent the current faces of fashion and society, respectively. (Ms. Prada's eponymous company will sponsor both the Costume Institute exhibit and the opening-night event.) Ms. Cussi is much more of a wild card. Like the appointments of such previous chairs as Mrs. Bronfman and, last year, Julia Koch, the wife of billionaire David Koch, Ms. Cussi's inclusion in this year's troika seems almost designed to accelerate her standing in New York social circles.

The Met's press office identified Ms. Cussi as a collector of contemporary art and a founder of Mexico City's Centro Cultural/Arte Contemporaneo, a museum. But in Latin America, she is still primarily known as the wife of Mexican media mogul Emilio Azcarraga Milmo, who was also known as "El Tigre" (that's "The Tiger," you gringos!). Azcarraga, who died in April 1997, is credited with building Televisa International S.A., the media conglomerate founded by his father, into the largest producer and broadcaster of Spanish-language programming in the world. Azcarraga was also the man who in 1988 threw $37 million into that 17-month black hole disguised as a sports newspaper, The National.

Azcarraga reportedly met and fell for the blonde (his third or fourth wife, depending on the source) while she was working as a weather reporter for Televisa-a bit of information that should deflate a bouffant or two among New York's patrician ranks. Although his marriage to Ms. Cussi ended in divorce, he reportedly was generous to her in his settlement and in his will. Ms. Cussi also made a big score when she sold her 16.9 percent stake in Televisa to Azcarraga's son, Emilio Azcarraga Jean. (A report in The Financial Times of London said that $400 million had been raised to buy out Ms. Cussi and another shareholder.

Since her ex-husband's death, Ms. Cussi has departed her post as vice president of the museum in Mexico City. She also made some headlines in London last year when the British Government tried to stop her from exporting from England an early, important Lucien Freud painting that she had bought at auction in 1994. Locally, however, Ms. Cussi is not much of a known quantity. Several observers of the social scene said they knew little about her. One Met source indicated that Ms. Wintour may have suggested Ms. Cussi as a potential chairman. But a spokesman for the Vogue editor said that Ms. Wintour was traveling and could not be reached for comment. Maria Kocherga, who cares for Ms. Cussi's art collection at the Mexico City museum, told The Transom that Ms. Cussi was also traveling and could not be reached for comment. No doubt New Yorkers will learn more about her between now and the time of Ms. Cussi's orchestrated invasion of the Metropolitan, which takes place, appropriately, on the anniversary of Pearl Harbor.