By Joanne Fowler
November 27, 2000 12:00 PM

Nan Kempner is having an identity crisis. Whether setting out for a wild boar hunt in France chez Count and Countess d’Ornano or a boat party down the Nile with the Gordon Gettys, the rail-thin, impeccably dressed Manhattan society grande dame isn’t sure how to describe herself on travel documents. “I’m not rich enough to be a real philanthropist,” she insists. “And I loathe being called a socialite. So I write ‘housewife.’ ”

Well, she does have a house. And she is a wife. But this isn’t a woman you’ll find chasing dust bunnies in Levittown. The place Kempner calls home is a sprawling 16-room Park Avenue duplex decorated with 18th-century Chinese screens and Persian carpets. There her days begin at 11 a.m. with breakfast in bed (toast, honey, coffee and a crock of Skippy chunky peanut butter) served l by the maid, who also does the housework. “Fortunately,” says Kempner, 70, “I don’t have to clean. Otherwise we’d be under six inches of dust.”

Rather, Kempner’s gift is partying, something she does on average four nights a week. Says fashion publicist Paul Wilmot, a frequent escort: “She calls me and says, ‘Two weeks from Wednesday I have a hole in my calendar. What are you doing?’ She can’t stand a night off.”

But the best soirees of all, observers agree, are the ones Kempner herself throws. “She fills up the whole apartment with people,” says Oscar de la Renta executive Boaz Mazor. “Every visitor from out of town is there.” In 1997, for example, when the late Princess Diana auctioned off her frocks at Christie’s New York, Kempner’s was one of the few private parties she attended. “She is the stereotype socialite,” says Allure magazine editor Linda Wells. “At a distance people can take potshots at her. But meet her for five seconds and that disappears.” Jewelry designer Kenneth Jay Lane, a frequent guest, agrees: “Nan is a very generous hostess.”

So generous that Kempner has persuaded 33 of her pampered pals to share with the hoi polloi some of their entertaining secrets for her new cookbook R.S.V.P. Valentino takes readers onboard his yacht T.M. Blue One for seafood ravioli and flourless chocolate cake; Annette and Oscar de la Renta open the doors of their Dominican Republic estate for a sampling of lobster salad and pineapple tart. “Nan is a great friend,” says de la Renta, explaining why he agreed to help on the book, the proceeds of which go for research at New York City’s Memorial Sloan-Kettering Cancer Center, Kempner’s favorite charity. “She doesn’t have a mean bone in her body.”

Kempner’s ease in entertaining can be traced back to her privileged upbringing in San Francisco. The only child of Albert Schlesinger, a successful car dealer (he was host to Henry Ford at the family mansion), and his socialite wife, Irma, Nan attended private schools and spent summers at a family home on Lake Tahoe staffed with chefs and maids. Too much time in the kitchen caused Kempner’s weight to climb to 140 lbs. by age 12. With her mother’s consent, a doctor prescribed a high-protein, low-carb diet. “I didn’t want to be a rotund woman,” says the 5’8½” Kempner, who eventually shed 40 lbs. and still wears a size 2 or 4.

Inheriting her mother’s style, Kempner bought her first couture gown at 19—a white Dior sheath. “If you start out that way, you end up a terrible clotheshorse,” says Kempner, who attends the Paris fashion shows twice a year, occasionally spending up to $10,000 per dress (“That’s the most expensive,” she says), often on half-priced samples. Says designer Bill Blass: “You can’t find anybody who knows as much about clothes.”

To ensure her pricey togs fit for decades, Kempner, a self-described “closet smoker,” does yoga five times a week and often walks instead of taking cabs. Recently she ruffled feathers by telling W magazine, “I loathe fat people,” but now regrets the comment. Still, Kempner makes no apologies for prizing beauty and admits to plastic surgery. “This isn’t a dimple,” she quips, pointing to her chin. “It’s my belly button. I had the whole thing pulled up 15 years ago!”

Her husband of 48 years, Thomas Kempner, 73, a member of the Loeb banking family, whose idea of fun runs more to hockey than hobnobbing, takes his wife’s antics in stride. “She’s a lady in every way,” he says. “I can’t remember her saying anything hurtful.” The couple met in 1951 while on a double date and married the next year, prompting Nan to end art studies at Connecticut College. Her entrance into Manhattan society soon after fell short of graceful. “I was huge, like a dirigible, and had to meet everybody,” recalls Kempner, who was eight months pregnant at the time with son Tom Jr. (now 47 and a Manhattan investment manager), the first of her three children. Nonetheless, she quickly became a fixture on the charity circuit. “As long as I remember, she was society,” says her son Jamie, 43, an investment banker like his father. Adds sister Lina, 45, a Manhattan artist, who recalls meeting guests Mick Jagger and Yves Saint Laurent: “There were nights I’d zip her dress up and she looked so glamorous.”

Indulging her passion for fashion, Kempner got her first job in 1967 as an editor for Harper’s Bazaar, then did a decade-long stint at French Vogue beginning in the late ’70s. Yet under the glitzy facade, her home life was in turmoil. In 1988 she and Tommy separated (although he never moved out of their apartment), the result of his seven-year affair with film producer Iris Sawyer. “Let’s face it” says a reflective Kempner, “it makes a marriage more interesting. I don’t know any man who hasn’t strayed.”

Now reconciled, the couple are planning a gala ball to mark their 50th anniversary in 2002. “We’re a wonderful balance to each other,” says Nan. “He’s disciplined, I’m the wild butterfly.” Tommy, who often slips away during his wife’s soirees and goes to bed, shares that view. “Someone told me,” he says, ” ‘If you get up on a Thoroughbred, it’s best to ride with a loose rein.’ ”

Joanne Fowler

Jennifer Frey in New York City