I often see an elderly woman in my Paris neighborhood waltzing down the street to her own imagined music, flashing a slightly demented smile at everyone she passes. Anywhere else, I would cross the street to avoid her. But she always wears a matching, if slightly kooky, outfit—like the red print skirt, loose cardigan and scarlet cloche hat she wore one day this spring—has great posture and is beautifully made up.

She clearly loves being herself. And she makes me think that in France, women might forget everything else as they age—but never their sense of style.

If there is a secret to aging well, French women must know it. At least that's what Americans think. We look at actresses like Juliette Binoche, 46, or politicians like Segolene Royal, 56, or superstars like Catherine Deneuve, 66, and figure that they must have special insights into the "maturation" process.

And even the average French woman—say, shopping along the Rue du Faubourg St.-Honore or enjoying a leisurely lunch on the Left Bank, or strolling through the Luxembourg Gardens—seems to defy the notion that, as one grows older, you either have to disguise that process with Botox, eye-lifts, lip plumpers and all sorts of procedures that convey a desperate "youthful" look, or else just give up altogether and let the ravages of time take their toll.

But do these women really have the answers when it comes to the aging process?

Women on both sides of the Atlantic realize that the keys to aging well are obvious, but challenging if you have bad genes, spend too much time in the sun or smoke a lot. But while American women, like me at least, approach personal care with practical efficiency, the French women I know regard the pampering of the skin, hair and body as an enjoyable, gratifying ritual.

Looking attractive, at any age, is just what French women do, especially the urban ones. For Parisiennes, maintaining their image is as natural as tying a perfect scarf or wearing stilettos on cobblestone streets. Beauty is a tradition handed down from generation to generation. "My grandmother always told me, `Never neglect yourself, not even in the tiniest details,"' my friend Francoise Augier said, with a sweeping head-to-toe gesture. The French actress Leslie Caron, still Gigi-like at 79, told me her mother's favorite saying: "Women's skin is too fair to go bare."

Not that French adolescents are any more likely than their American counterparts to heed their mothers' advice. My neighborhood esthetician, Martine, is concerned that so many of her young clients (age 12 and up) go outdoors without sunscreen. Maybe she shouldn't worry. A survey by the market research company Mintel found that 33 percent of French girls between 15 and 19 are already using anti-aging or anti-wrinkle creams.

Though French men are clearly interested—they shamelessly ogle women on the street—beauty is a female topic. When, over dinner, I asked a grandmother of three how she managed to stay beautiful, she deflected my question, saying, "I never discuss these things in front of my husband."

The No. 1 response to my informal survey of French women about the years of magical aging is not gaining weight. Ever. If a French woman happens to see an additional kilogram or two on her bathroom scale, she will do whatever is necessary to force the needle back where it belongs. "I keep my weight steady, no ups and downs," Caron said. "I avoid all excess." She claims to eat all kinds of food in small—her friends say minuscule—portions, and she doesn't drink alcohol. It's not so much that "French Women Don't Get Fat," as the title of Mireille Guiliano's best seller had it. Rather, French women won't get fat.

Not that they exercise. When my husband and I arrived in Paris and asked our personal banker -- everyone has one -- for a gym recommendation, her response was: "Why? Gyms are a form of torture." It seems the only acceptable way to burn calories is to walk.

If French women don't walk enough to stay en forme, there is always a pill, a lotion, a machine or a treatment to do the trick. Pharmacies have counters full of diet and figure-improving remedies. One cream promises "accelerated reduction in the areas resistant to diet" (hips, thighs and buttocks). Capsules assure a flatter stomach in four weeks. A poster recently plastered all over Paris Metro stations advertises a tiny Slendertone "Electronic Muscle Stimulation" belt that claims to provide, in a single session, the equivalent of 120 abdominal crunches. (It's available in the United States, too.)

French women also recommend facials, massages and spa "cures" in their campaign against wrinkles, cellulite and saggy bottoms, bellies and breasts. One spa favorite is thalassotherapy, the seawater-based treatment that originated in France. It involves water jets, seaweed wraps, mud baths and sea-fog inhalation, meant to improve circulation, promote sleep, tone muscles and reduce cellulite. Some women are resourceful enough—or have legitimate medical reasons, like arthritis—to get doctors' prescriptions for weeks at their favorite spa. That means government health insurance covers much of the bill.

As for makeup, French women of almost every age (except those teenagers) regard less as best. Heavy foundation has a tendency to emphasize wrinkles and pores, and most women avoid it in favor of a bit of blush. Those who do use foundation make sure that it blends with the skin, often by applying it just after moisturizing. The idea is to look as natural as possible: a little color on the eyelids, mascara, maybe a bit of eyeliner and lip gloss.

Of course, it's easy to look natural if your skin is great. And that may be where the French secrets really are. According to a 2008 Mintel report, French women spend about $2.2 billion a year on facial skin care—as much as Spanish, German and British women put together. If you happen to use the bathroom in a French home—something that is not considered polite, by the way—you might see a line of skin care products rivaling a shelf at Duane Reade.

There will be day creams (with sunscreen), night creams (without it), re-pulping creams, serums, moisturizers, cleansers, toners and salves for anything from orange-peel skin to varicose veins. But you might not find much soap. Caron says she doesn't use it on her face or her body (except for "certain places"). Madame Figaro magazine recently quoted the French actress and TV presenter Lea Drucker as saying, "The day I stopped using soap, my life changed." Post-transformation, she uses a hydrating cream.

As in America, some women in France turn to dermatologists for their skin care, and their visits are likely to be covered by health insurance. Even the generous French system does not pay for Botox, collagen or hyaluronan injections, nor for "lifting" and most other cosmetic surgery.

That doesn't stop French women from having "something done."

The objective of plastic surgery in France, according to Dr. Michel Soussaline, a Paris surgeon with more than 30 years of experience, is "to keep the natural beauty and charm of each individual woman, not to fit some current ideal of beauty." After all, trends change. In the United States, he says, women who spend a lot of money on face-lifts want to show off their investments. (Maybe that explains the lopsided smile and smooth cheeks that the American actress Ellen Barkin, 56, recently displayed on the Cannes red carpet.)