Sitting down is a complicated maneuver when you're wearing low-rise jeans.

"They slide off my butt," says Tiffany Lambert, 14, of Altamonte Springs, Fla. She is hanging out at the mall with friends, who all wear low-slung jeans and tiny tops.

"You kinda have to pull them up, then hold them up when you sit," explains Rachel Richards, 15, of Longwood, Fla.

"And not lean forward," adds Tiffany.

"Or your underwear sticks out," offers Rachel, giggling.

Such is life with skin-baring fashion. But relief is on the way. Skin is no longer in, say the trend-spotters. Not even for teens and twenty-somethings.

Miniskirts, skimpy tops and those embarrassing, thong-baring jeans are on the way out. They are being replaced by high-waist pants, long-sleeve tunics and knee-grazing skirts.

The latest fashion watchword is modesty.

A word long missing from the style lexicon, it's suddenly on the tongue of every trend-watcher, on the runways of London, Paris and New York, and in the latest issues of magazines as different as Seventeen, InStyle and Vogue.

"Naughty vs. nice," trumpets Vogue's cover. And inside: "The end of the reign of the teen pop temptress. . . . Britney, Paris and Christina are overexposed in every way."

InStyle suggests readers steal the preppy '50s look of Faith Hill in "The Stepford Wives," and it praises the "bookish refinement" of Hilary Swank's buttoned-up white blouse and knee-length gray skirt.

Hilary Duff, looking squeaky-clean in a demure dove-gray jacket over a white top, is Seventeen's cover girl. (Could old-fashioned names such as Hilary also be part of the trend?)

In a single season, fashion has flipped from cheesy to cutesy.

Fashion experts suggest a number of reasons for the about-face. Some welcome it; others view it with suspicion. But all agree it is happening -- from coast to coast, and for everyone from tweens on up.

"The first reason that comes to mind is the most obvious: the fashion pendulum," says Rachel Weingarten, a trends expert and president of GTK Marketing Group in New York. "Fashion is always swinging from one extreme to the other: mini to maxi, tight leggings to baggy pants, bare to covered up.

"Think of Madonna, how she's gone from bustiers to mumsy dresses and floral frocks."

There's also the current backlash against showing too much skin, she says -- against Abercrombie & Fitch's naked catalogue models, against Janet Jackson's breast flash during the Super Bowl halftime show.

"People have had enough. Even sexualized pop stars are starting to scale back," she says.

The backlash against revealing fashions has been unusually forceful in recent months, says Lyn Mikel Brown, an associate professor of women's gender and sexuality studies at Colby College in Waterville, Maine.

The reason: Marketers have targeted "even the littlest girls with sexualized clothing and messages."

"I think for many parents, myself included, this was the most offensive part of the trend," says Brown, mother of a preteen daughter. "It's hard to explain to an 8-year-old -- and as a mother I resent the fact that I'm pressed to do so -- why certain clothing suggests certain things to certain people."

In other words, try explaining "hooker chic" to an 8-year-old.

Catherine Stellin, a vice president at Youth Intelligence, a trend-tracking company in Los Angeles, agrees the "slutty look" is passe.

"It's oversaturated," she says. "The way to stand out is to go against the grain. Right now, that means having a more covered-up, sophisticated look.

"It's nice," she adds, "when trends work in parents' favor."

In interviews with girls and young women across the country, "the word 'trashy' came up a lot," Stellin says. Teens who a few months ago emulated the provocative style of pop idols such as Jennifer Lopez now are spurning those looks as "trashy," she says.

Their new role models are fresh-faced stars such as TV's Mischa Barton of "The O.C." and Amber Tamblyn of "Joan of Arcadia." The modesty trend is also tied to the political climate, says Stellin. "There's this sense of uncertainty -- about the economy, the threat of terrorism, the war in Iraq, the prison scandal. These are big issues in people's minds, issues that call for more serious clothing."

Sexy style is the culmination of two major lifestyle forces: "The sexual liberation movements of the 1970s and the physical fitness craze of the '80s. They merged during the '90s, slowly but surely," says David Wolfe, creative director at the Doneger Group, a trend-forecasting company in New York. "Now low-rise can go no lower -- I hope."

Fashion has reached the point of "sleaze fatigue," says Jamie Ross, another consultant with the Doneger Group. "Bare just doesn't look new anymore, and fashion needs to look new all the time."

This quest for newness, along with the marketing hype that accompanies each new trend, troubles Brown.

"Whenever there's a dramatic shift, it's a marketer's dream. It means there's a whole new line of clothes to market," she says. "I suspect clothing manufacturers are gleeful and are pushing this big-time."

Also, watchwords such as "modest" and "demure" raise a red flag for Brown.

" 'Modesty' sounds like pre- or post-feminist jargon for stepping back, acting nice, not making waves," she explains. "I worry that what will follow is a push for girls to be more accommodating and conservative."

She would rather girls be creative, bold and independent, no matter what trend they follow.

Trend-spotters say the days of overexposed skin are over: Miniskirts are out, knee-length skirts are in. Low-rise jeans make it difficult to sit without showing too much skin, teenage girls report.The latest fashion watchword is modesty. Magazines showcase styles that are sophisticated and demure, squeaky-clean and preppy.