In the sweet fantasies of designers, spring 2003 will bring a bold unveiling of thigh and even, upon occasion, a shadowy knoll of derriere. Sitting alongside a runway, it is quite something to see a professional model's extraordinary legs -- up close, without benefit of airbrushing and with graceful muscles flexed -- balanced atop a pair of stilettos and rising heavenward toward a wisp of a dress.

Abbreviated hemlines have appeared on the runways for some time under labels including D&G and Versus, but they were mere spice in seasons dominated by conservative pencil skirts and modest A-lines. Now minis have become the featured item on the menu. This is one of those rare instances when the fashion industry has made a pronouncement of such clarity that those who still find credence in hemline mandates already are logging extra miles on the elliptical trainer.

Typically, fashion trends can be traced to a defining moment on a single runway. Christian Lacroix propelled the tutu silhouette of le pouf into fashion history, for example. Prada popularized dowdy chic. Yves Saint Laurent Rive Gauche, under designer Tom Ford, fueled the rise of the peasant blouse. Lineage is not so clear on the return of miniskirts, which were last worn in the late '80s and early '90s with black, opaque hosiery or, on unfortunate occasion, with anklets and high heels. This time, minis crept up on us.

A short silhouette "was in virtually every big collection," says Peter Marx, president of Saks Jandel in Chevy Chase. "Even if you wanted to buy around it, you couldn't."

Designers who presented their spring collections in Milan last month were the most vociferous and unified in their support of the micro-mini. Donatella Versace, who pushes high-class sleaze with the hypnotic skill of a silver-tongued hustler, cut all of her dresses short. What they lacked in length, they also lacked in breathing room. There were a few pleated skirts and shimmying baby-doll dresses. But mostly the clothes followed every curve of the body without apology -- except when the tiny skirts were slit on the thigh to ensure that no one's imagination would have to break a sweat.

The Versace collection might prompt a conservative observer to ask: Who would wear that? The more salient question, however, is: Who could wear that? Because if a woman could confidently wear a psychedelic mini and cause jaws to drop in admiration and envy, well, wouldn't she?

A chorus of other designers are cheering on short skirts and dresses, including Anna Sui, Celine's Michael Kors, Karl Lagerfeld at Chanel and Balenciaga's Nicolas Ghesquiere, who likes his stitched out of tropical flora-printed neoprene, the skintight fabric of scuba suits. But only Gucci's Tom Ford shares Versace's level of preacherly enthusiasm for short, declaring after his October runway show that his faith in mini-dresses was so complete that, contrary to industry tradition, he would not substantially lengthen his creations to appease the concerns of more modest shoppers.

Ford steered clear of raucous colors and harsh prints, instead choosing soft pink and gentle patterns of cherry blossoms and fluttering birds. The mood of the collection elaborates on a Japanese aesthetic that Ford explored for his fall collection. But this time, he used about a quarter of the fabric.

It's worth noting that while Ford was celebrating thigh-skimming kimonos, notable Japanese designers -- Issey Miyake, Yohji Yamamoto, Yoichi Nagasawa, Junya Watanabe and others who presented their spring collections in Paris last month -- avoided short skirts altogether.

"Short is very, very difficult to wear; only a few people can wear it very, very well," says Henri Peker, owner of Washington's MicMac Bis, which devotes about 60 percent of its retail space to Japanese labels. "For Yohji or Miyake, there was no short they were proposing. We didn't have to think about it."

One might wonder, however, what the rest of the fashion industry was thinking. Realists could reasonably ask why designers would spotlight a style that looks best on a lithe figure when more than half of adult Americans are overweight. Much is often made of an alleged correlation between the rise of hemlines and an improvement in economic fortunes. Short skirts are supposed to reflect a robust economy. Cathy Atkinson, owner of All About Jane in Adams Morgan, calls this spring trend "forced optimism."

That relationship, however, is pure myth, says Valerie Steele, a fashion historian at New York's Fashion Institute of Technology. If there is an economic explanation for rising hemlines, it is that designers are searching for something fresh to entice customers. After several years of skirts that hovered at the knees, a shorter dress evokes youth, sportiveness and sex appeal. It is a different look that surprises the eye, an unfamiliar silhouette that can energize a wardrobe. And retailers are betting that Washington women who can, will wear it. Judiciously.

"I think women in D.C. are so practical, even in their twenties. If they're going to invest in something, it will be something more timeless. But I think people will want to have one or two short skirts in their wardrobe to feel sassy," says Atkinson. How short will she endorse? Mid-thigh.

Retailers also argue that short skirts are not the province of a single generation. For many women, "as they age, their legs are their best asset. Now, would I put [a skirt] up to my crotch? The answer is no," says Nancy Pearlstein, the owner of Relish in Chevy Chase. "But I've waited on women in their forties with unbelievably fabulous legs. They're young at heart and young-looking and they look great."

"This is the bottom line: I'd rather see a 40-year-old woman in a short skirt than one walking around with her belly hanging out," says Pearlstein, noting that designers are no longer obsessed with midriff-baring tops. "I'm glad that fad is gone."

Why Short Is Sexy The current advertising campaign for Victoria's Secret asks: What is sexy? In one instance, the model Gisele Bundchen appears in bikini briefs, garters and a plunging leopard-print brassiere. On another occasion observers are given a shadowy glimpse of her wearing a whiff of a lace skirt. Or is it a slip? Sexiness is boiled down to bareness. And on the designer runways, bareness is translated as micro-minis and three-inch heels.

"I think most women wear a really short skirt when they want to feel sexy," Atkinson says.

But why is short sexy? Could it be that the senses are not aroused simply by the rationed fabric and a tight cut, but by something more complicated? The historian Steele notes that few people would describe a young woman wearing shorts, socks and sneakers as being provocatively dressed. But if she wears the shorts with thigh-highs, that's an altogether different story. "It's not just the expanse of leg that's revealed, but how it's exposed," Steele says. That three-inch peek of naked leg between the shorts and the stockings is startling. It is "deliberately sexualized," she says.

From the beginning, the fashion industry has been ambivalent about the message of a micro-mini. When couture collector Sandy Schreier remembers the pleasure of wearing the miniskirts of the '60s, appearing sexy was not her goal. Instead she recalls the cultural and fashionable "youthquake" of the time: Peggy Lipton's "Mod Squad" cool, go-go boots, Mary Quant minis and Vidal Sassoon haircuts.

"Was there anything sexy about the Courreges and Cardins of the '60s? They were worn with baby-doll shoes," Schreier says. "When I wore micro-minis, I wanted to look like I had walked out of Diana Vreeland's Vogue magazine."

The point of Vogue, particularly under Vreeland's flamboyant reign, was to epitomize chic, not sexiness. The two are not mutually exclusive, but rarely are they present in equal measure.

When micro-minis made their return in the '80s and '90s, they were worn with opaque tights, and the effect was of tomboyish agility, dancer chic and sprightliness. When tantalizing miniskirts were paired with high heels, gazelle legs and . . . anklets, the socks stirred up a nymphet image that landed like a cold splash of water on now dangerous sexual ruminations.

"Is this sexy?" Schreier asks. "The body is, yes, but the clothes? No.

"Even if you have good legs, the more you show, the less mystery and the less sexy you are."

Sexiness has always been conveyed by coy allusion and the knowing tease. What is cleavage but an enticing suggestion of what lies below? "Nowadays our assumption is it's sexier the more you strip off," Steele says. "Historically, there was a strong belief that concealment is sexually alluring because it arouses curiosity."

The fashion industry has always known this to be true even if, upon frequent and reckless occasion, it ignores it. Versace knew this when she crafted the scarf dress with the plunging neckline that was made famous by singer-actress Jennifer Lopez. What made the gown so captivating -- aside from the glorious body inside it -- was the constant threat that at any moment the delicate fabric would be caught by the tiniest breeze and heaven would be revealed, if only for a moment.

In the fall YSL collection, similarly, a smoldering black blouse is alluring because only satin ribbons keep it from slipping off the body, and they are attached by threads that seem as fragile as a spider web.

Sexiness is crafted out of hints, teases and possibilities.

When a woman sits in a micro-mini, observers are taunted by the possibility that the skirt will rise to shocking heights or that her legs will splay open in a moment of distraction. But if the skirt actually shifts up or worse, the result is embarrassment all around. Sexy and shocking are not synonymous, although they are sometimes assumed to be. The remedy, of course, is to refrain from sitting or to keep one's thighs pressed close enough together to crack a pecan.

Behind the Mini The sexiness that the best of the new collections exploits is the perfect balance of shock and femininity. Sexiness exists in the gray area separating polite society from the demimonde, the fantasy of "Pretty Woman" from the reality of a prostitute and her pimp. Gianni Versace created the template for high-low style. He transformed the miniskirted streetwalker into the prototype of the fashion person, observed Richard Martin, the late curator of the Costume Institute at the Metropolitan Museum of Art.

Now sexiness unapologetically takes its cues from a kind of MTV feminism that idealizes the strutting gait of the prostitute and finds power in her corporeal ease. Witness the proud hawking of the body on the runway, the concert stage, in a Christina Aguilera video or at a cocktail party. (Machismo takes its cues from the street as well, with men adopting the style and the gestures of the corner thug as a way of establishing their manliness.) Fashion hasn't co-opted the streets; fashion is street style with more expensive fabrics, a finer finish and better shoes.

The line between the street and the salon began to blur dramatically in fin de sie{grv}cle Paris, says Steele, who curated an exhibition at the Fashion Institute of Technology that focuses on late 19th-century France. In Paris, where the fashion industry was transforming and becoming a more public, trend-driven business, there was a convergence. Courtesans and actresses, who were only a hairbreadth apart on the social ladder, became fashion role models as they glamorized themselves, wearing such items as colorful lingerie -- scandalous because the colors suggested that it was meant to be seen.

The result was that it became increasingly difficult to tell, simply by looking at the clothes, the difference between a strumpet and a socialite. Respectable clothes picked up the scent of tawdriness. Wicked attire entered upstanding society. And for women, even now, that has been a boon. When everyone is pulling from the same rack of short, tight frocks, who can tell the difference between naughty and nice? In a bar, a woman can flirt in a short skirt and her "reputation" will remain intact. She can be a sexual spectacle in a mini-dress on New Year's Eve and take a deposition a few days later wearing a pantsuit. A short dress becomes even more enticing because the nature of the woman wearing it remains a mystery.

"That's part of the tease," Steele says. "Fashion enabled women to express sexuality in a way that was socially acceptable."

Right Legs Only In fashion's most pedestrian moments, sexiness is confused with the clumsy spectacle of a near-naked body. When pop stars talk unconvincingly about being comfortable with their sexuality, they're usually referring to a revealing romp in a video. And the great flaw in Tom Ford's presentation of beautifully crafted mini-dresses was his decision to send several models down the runway wearing bikini briefs and short kimonos billowing open to reveal nude torsos. The sensuality of his well-balanced minis and of an elusive truth was marred by this nearly gynecological display of flesh.

But a miniskirt with a well-considered cut -- one that seems to murmur a private bedroom conversation, that conveys the subtle threat of a glimmer of rump -- can cause temperatures to rise.

When the miniskirts arrive in stores in early spring, they will surely spark cries of irritation from those who lob the phrase "real women" -- as if it were a conversational hand grenade -- into discussions about fashion.

But miniskirts are not democratic. They are not fair. They are not a right. Most women probably will not wear the tiny skirts but will instead simply raise their hemlines to a point that is fresh and flattering. Some will not feel comfortable in shorter lengths at all. A few will not wear them because they'll be shocked to discover they're just as expensive as skirts that skim the knees.

But some women with great gams will buy micro-minis and they will look splendid. These women will hint at a wild side. They will allude to a naughty secret. And when they drop something, they will always remember to bend at the knees, never the waist.

Versace's short skirt reveals a lot of leg.Chanel, left, and Versace, above, turn up the heat (could it get any hotter?) by raising hemlines yet again for their spring collections.Spring offerings from Gucci, above, Anna Sui, right, and Balenciaga, far right.Mini history: Ralph Lauren created a skimpy leather ensemble for spring 1994, far left; center, the sporty look of Courreges for spring 1992; British designer Mary Quant, above right in a 1967 photo, is credited with starting the miniskirt revolution.By July 1967, the mini had made it to the street in the States.Versace's short skirt, gathered up even shorter for good measure.Chanel, left, and Versace turn up the heat (could it get any hotter?) by raising hemlines yet again for their spring collections.Spring 2003 offerings from Gucci, left, Anna Sui, center, and Balenciaga, right.From left, Ralph Lauren created this skimpy leather ensemble for spring 1994 and Courreges the sporty look in 1992. Mary Quant, above right, started the whole thing with her miniskirt in 1967.