For many years, I have attempted to persuade my wife that the reason I cannot remain in a clothing store for more than about six minutes is that stores provide insufficient oxygen. It is pure physical need, not antagonism to the mission at hand, that sends me running.

Now I have met Paco Underhill, and my argument has been undermined. But only slightly. I am now willing to admit that, technically speaking, stores may not be engaging in oxygen deprivation. However, I am authoritatively informed that I dread clothing shops because (a) people are constantly asking if they can help me, (b) the signs are written for women, (c) the physical design caters to women, and (d) there's no comfortable place for me to sit, which is what, as a man, I am supposed to do.

"Look at this place," says Underhill, steering me to a table piled high with brassieres. We're in Victoria's Secret -- alien territory for almost any man, for sure, but that's Underhill's point: Your average man couldn't buy something here even if he had orders to. Nothing indicates just how one might go about choosing an item of intimate apparel or how the sizes work. Some of the merchandise is displayed in a jumbled mass -- a casual disarray that a man would find hopelessly confusing. There are no unmarked bags so the guy can go back to the office without getting ragged about buying women's stuff. And in the event the guy is here with a woman, there is no place to park him.

"It's almost all focused on women and yet we are in a culture that says men and women are equal," says Underhill -- retail anthropologist, shopping spook and founder of Envirosell, one of the rapidly growing number of consultancies that examine in exhaustive detail where, how and why we shop. During our visit, I count 74 women in the store and, besides us, one man.

Underhill is a tall, gawky fellow, a diplomat's kid who taught psychology until he realized that retailers would pay big bucks to learn precisely why their customers do or don't buy -- a set of truths Underhill assembles through surveillance cameras and personal observation of your every move in a store: where you glance, what you touch, when you leave. He checks the height of the merchandise display, the width of the aisles and their impact on a woman's subconscious sense of the odds that someone will brush against her rear. He has gathered compelling evidence that if a woman's butt is bumped as she shops, she will wheel and flee the store.

So Underhill understands why Victoria's Secret displays everything out on tables, on racks, available to be touched, caressed, mauled. No women's store would dream of having it any other way. Retailers know -- or if they don't, dozens of Underhills will tell them -- that female shoppers touch. "They are getting pleasure out of the search," Underhill says. "They touch and feel as they walk. Men look for one thing and if they can't find it -- I'm going to the jungle to hunt bear."

In the men's department of your traditional department store, the underwear and shirts are wrapped in plastic. No touching is going to occur, so why expose the merchandise to the elements?

But isn't it possible that men might like to touch if only they had a chance, if only they were led to believe that it's okay, it's part of the routine?

Such a heresy would involve change, and change has not been part of the men's clothing business. Rich wood paneling, brass appointments and bowing and scraping salespeople are what retailing to men has been about throughout most of this century, and likely will be well into the next. Men are, in the view of much of the fashion industry, lugs, creatures of habit and fear, encumbrances in the otherwise smooth process of separating women from their dollars.

For generations, the rules of retailing have remained largely unaltered: Women shop, men buy. Women know the lingo, men need to be told the rules. Women are gatherers, men are hunters. Women buy trends, men buy clothing. Women find the goods, men sit in big easy chairs known in the industry as "plant chairs" because it's where you plant your husband so you can get to the business at hand.

The parade of gender stereotypes marches on: Men don't talk. Men scare easily; if a salesperson comes on too strong, men simply walk out. Women want what's new; men are perfectly happy to wear the same thing forever.

And yet . . . you may have noticed a few changes in our culture in the past 40 years. Something about feminism, women joining the work force, gender roles shifting. So how can this difference in retailing to the sexes persist? In a country that worships selling, how can clothing retailers virtually dismiss half the population? In an era in which every consumer whim, each nuance of consumer behavior, is measured by focus group, phone survey and surveillance camera, are men really so different from women that no one has figured out how to get them to purchase as many clothes as women do? Or is it just possible that men and women have already changed and the people who sell to us haven't yet caught on?

A man can be invisible in stores. At a Banana Republic, Underhill and I watched a salesman approach a striking young woman. "Can I help you?" he asked. She ignored him. He asked again. While the salesman stalked the woman, a fiftysomething man stood not three feet away, his entire body shouting for attention, though he remained mute. The rejected salesman stared right through him. Finally, fiftysomething's wife stepped forward and said, "But you can help my husband." No response. She said it again. And a third time. At last, the clerk said, "Yes, ma'am."

"Is there a chair here for my husband?" she asked.

Leah Brown needs no chair. Brown is a championship shopper, a woman of leisure from Potomac who makes the rounds of her favorite stores a few times a week -- Neiman Marcus, Saks Fifth Avenue, Nordstrom, the malls.

From childhood, when she would head downtown after school to haunt the grand halls of Garfinckel's and Woodward & Lothrop, Brown has used shopping as adventure and entertainment. "I don't know why I want these things," she says, "but I'll tell you this: I never have remorse. I only feel bad for the things I didn't buy."

Brown has a closet larger than many people's apartments. She's a seventysomething Barbara Walters lookalike who is married to Sidney Brown, a wealthy octogenarian developer. On a lunchtime lark at Neiman's, she touches gowns, dresses and scarves as she walks through the departments. What feels and looks right, she buys. "Need doesn't mean anything to me," she says with a laugh. "What do we need? Just to be covered, right?"

Strolling through the store with Helen Moody, a shopping consultant and keeper of Brown's extraordinary closet, she selects five shirts and a bathing suit for her son's birthday present ($457), picks up a scarf from a table of sale items ($200), admires and acquires a $795 cashmere sweater despite the 103-degree heat outside, chooses a Missoni skirt and top ($1,620), uttering just four words ("I'll do these together"), fingers and takes a purple, white and green dress set ($1,360), grabs a Gaultier cream-colored top ($240) and throws in Gaultier black tuxedo pants ($1,005). Elapsed time: 34 minutes. Cost: $5,677, tax, lunch and consultant not included. How she knew she was done: "When I've run out of time."

If she is a retailer's dream, Brown is also an extreme example -- she is, after all, married to a megamillionaire -- but she represents the industry's fantasy of how all women might behave if they had the bucks: impulsive, emotional, someone who buys both on her own and with friends. "When I walk in that store, I become stupid," Brown says. "It's an escape for me."

Social mores evolve, and women's relationship to shopping may well be easing away from infatuations like Brown's. It's not quite as acceptable these days for women to admit a love of shopping. But Brown pays that no mind. She believes most women love the quest, and retailing research backs her up -- despite time stress, the changing workplace and other strains of modern life. "It's not the thing to say, but as I got older, I don't care. We love shopping. I focus in and when I'm in the stores, I don't smell, see or hear anything else. The day my [first] husband left me, Helen took me out to look at bride's dresses, to get ready for Number 2. She got me up and out -- to the stores."

What has changed? Only everything. When the shopping mall was invented, women were moms, teachers, nurses, waitresses and that's about it. Now women are anything and everything.

As this revolution has occurred, what has changed in how clothing is sold? At first glance, not a whole lot. Women still make 80 percent of all clothing purchases. A recent survey by the Wirthlin Group found that while 67 percent of women decide by themselves which clothes to buy, only 48 percent of men do so. At Kmart, for example, women often outnumber men in the men's department by 3 to 1. Those men who do shop tend to be under 30; once they settle down with a woman, most men disappear from the stores.

And no, this is not changing in the direction you might think it is. The 1999 National Benchmarks of Shopping Patterns survey shows that the proportion of mall shoppers who are men is dropping -- from 36 percent in 1990 to 31 percent in 1998. Men spend considerably less -- in both time and money -- than women do. When men do enter a mall, clothing is hardly atop their lists: While 21 percent of women at the mall stop into a women's clothing store (their favorite destination of all), only 6 percent of men will visit a men's shop (far behind their favorites -- music, electronics and book and card shops).

Chicken, egg, whatever: The fact is that the square footage of mall space devoted to men's clothing is plummeting, down by nearly half in this decade alone. Malls, of course, are hardly the whole shopping universe; the rise of big box discounters (Target, Wal-Mart, Kmart), warehouse clubs (Price Club, Sam's), unisex clothing stores (the Gap and its many imitators), catalogues and e-commerce has altered the calculus of shopping. But the basic rule of retailing by gender applies to all of the above: While women only gain more people to shop for as they grow older -- boyfriends, husbands, children, grandchildren -- "men tend to lose interest in shopping as they age," says Bill Roop, president of Stillerman Jones, the consulting firm that conducts the annual shopping patterns study.

You might not know it from looking at menswear stores, but men's shopping behavior has evolved. For one thing, men buy some items they never did before. Vacuum cleaners are now sold by their amperage -- their raw power -- because market research says male shoppers want "maximum suck." Men buy some curtains, sheets and underwear, items they used to rely on mothers, wives, sisters or girlfriends to buy. But the marketing of most products remains squarely aimed at women.

On the surface of the apparel game, traditional roles seem stable. But bubbling from below is a deeper kind of change, an evolution not immediately apparent from sales statistics. What if the end of the century also foretells the end of shopping as social activity? What if the social purpose of the mall is spent?

When shopping became the great American avocation, the suburbs were just beginning to sprawl. Women, still largely home-based, needed an escape from the social hell of suburbia, where each family was now imprisoned on its own half-acre, ripped away from the easy interactions of urban row houses, city grids and ethnic neighborhoods. The store -- and later the mall -- became a prominent public place for women to congregate.

This worked splendidly for two or three decades. Then came two-earner couples, the "second shift," women who told their men to go out and get their own shirts.

At the dawn of the new millennium, "women are finding their social outlets elsewhere -- at work, or in the new third places, the coffee shop, any place that has refreshments and is smoke-free," Underhill says.

Wendy Liebmann, president of WSL Strategic Retail, a New York company that studies how Americans shop, believes we are witnessing the fading of old distinctions between men and women -- destination shoppers vs. emotional browsers, I'm going to get six pairs of brown socks vs. I'm going shopping. "Women are now very busy, perhaps busier than men, and so women are becoming more like men in shopping," she says.

And yet. "Women still talk about, with a big sigh, `Some time for me,' " Liebmann says. "When they get that time, women stand at the front of their department of the store and say, `Wow, look at all this stuff for me.' Whereas the man stands there, sees all that, and says, `Where's my wife?' "

Essential differences remain. Women will still phone a friend and say, "Let's go shop for shoes." Men, for the most part, do not do this. Here it gets tricky. A new study by Iowa State University consumer psychologists found that black men have a stronger interest in dressing well than do their white counterparts. For black men, shopping can be a social activity in a way that it is generally not for white, heterosexual males, says Margaret Rucker, a consumer psychologist who has surveyed hundreds of men in studies at the Division of Textiles and Clothing at the University of California at Davis. "It's a lot more socially acceptable for black men to appreciate color coordination and fine fabrics. They tend to have a greater appreciation of the impact clothing can have on impressions. Black and Hispanic men find it important to dress to fit in and to succeed, where white men tend to look more at comfort and clothing as tools."

In the vast academic literature about fashion, studies like these examine the different ways in which men shop, or the various styles in women's behavior. But until recently, little has been written contrasting the sexes. Lately, management and consumer psychology journals have been exploring something called the New Man, a creature who is reacting to feminism and reassessing masculinity by growing more narcissistic, more nurturing. That makes him more aware of fashion, more concerned about his body and his looks, more of "an active consumer in the pursuit of his sense of self," as a British researcher put it. This New Man is, in other words, becoming more like women.

The differences between how clothing is sold to women and how it is hawked to men do not all descend from the central assumption that women know what they're doing and men are retail Neanderthals. No, stores manage to look down on women, too.

Women, most retailers believe, are highly impressionable. Thus, the reasoning goes, all a store need do to sell to them is concoct an alluring fantasy. "Reality is, `I need a suit,' " says Helen Moody. "Fantasy is, `Maybe I'll go find a dress and that dress will make me look fabulous and then I'll find a man.' And department stores are set up to take advantage of that: The first thing you see is cosmetics, so they're immediately suggesting that you have acne or you need to fix your face."

Need is hardly a factor. Fantasy is such an essential ingredient that trying clothes on is often satisfaction enough for women; retailers know that most of what women take into the dressing room will stay there. With men, on the other hand, if you can get them to try it on, it's just about sold. Want some numbers? Underhill's company studies conversion rates -- the percentage of shoppers who actually buy -- and has found that 65 percent of men who try something on will buy it, versus 25 percent of women.

Men, unlike the fairer sex, are driven almost exclusively by need -- or so tradition has it. Twentieth-century tradition, anyway. For most of history, it was women who got what they needed -- and little more -- while men were the fops decked out in jewels and plumery. It took the Industrial Revolution to turn that around. Removed from the countryside into the more egalitarian city, well-to-do men donned suits that gradually became more of a uniform. Men came to value utility over style. "They shop the way they drive," Underhill says. For fear of losing face, men don't ask questions. They take no apparent joy. They accomplish their task and move on.

The way clothing is sized demonstrates how the industry has interpreted this distinction between men and women. Men, for example, usually get free alterations on new clothes. In a holdover from the days when it was assumed that all women sewed, women get free nothing.

And men's clothes are far more likely to fit reasonably well to start with, because men's clothes are based on a "dual sizing system," which means that men's stuff is measured in two directions -- waist and inseam for pants, neck and sleeve for shirts. (Of course, many men haven't a clue what their size is. Underhill's cameras have even caught a man at an underwear display reaching around, pulling up the waistband of his underpants and checking out his size.)

Women's clothes are much more of a crap shoot: 6, 8, 10 -- "You're on your own," Rucker says. "It's much easier for the retailer, because all they have to carry is a few sizes, without worrying about stocking every possible combination of waist and inseam." Women accept this, in part because stores make it so easy for them to return items, which happens, depending on the store, to as many as half the items sold.

Department stores emphasize the link between fantasy and women -- in their ads, in store design, in the basic psychology of their sales approach. Check out the names of the departments at Nordstrom. As they browse -- and it is assumed that they have plenty of time to wander through the entire store -- women are expected to divine the meaning of signs that say "Savvy," "Encore," "Town Square" and "Individualist." One floor away, in the men's department, which typically is conveniently located right at the entrance so the idiots do not have to look for anything, departments are named with no such whimsy: "Men's Suits," "Men's Furnishings," "Men's Shoes" and even "Men's Restroom." Good luck finding the women's.

There is a single exception to this arrangement. One department in the men's section sits under the title "Faconnable," which is apparently supposed to sound like "Fashionable." Pointing across the store, I randomly asked four men what they thought might be under the word -- an area that appears to consist primarily of clothing that is neither blue nor gray. Here are their uncensored guesses: "Very expensive suits." "The stuff nobody wants." "Fruity stuff." "Gay clothes."

Over the past 20 years, big stores transformed their women's departments from places that set the fashion agenda and offered the ladies "better dresses," "juniors" or "sportswear" into a collection of mini-shops, each defined by a brand name. Stores simply expected women to know what each designer makes and be willing to wander the floor. Men's departments remained largely unchanged: "Suits," "Accessories," "Shoes."

In a department store, men's clothing is in one place. Women must zigzag throughout the building. "Blouses are on two different floors in eight different departments," explains Moody. "They don't want you to know where it all is because on the way from blouses with long sleeves to blouses with short sleeves are the sheets and towels, and they know you're going to say, `Oh, I need towels,' and you never get to the short sleeves, but that's okay, because they know you're coming back day after tomorrow. Whereas the man is not coming back."

Relish, Nancy Pearlstein's classy but funky boutique on Wisconsin Avenue in Chevy Chase, attracts the kind of woman who likes to stay current and knows what she likes. So Pearlstein, who spent 10 years as a buyer at her family's top-drawer men's shop, Louis Boston, knows firsthand the difference between men and women.

Relish reflects the greater confidence and playfulness that retailers assume their female customers will bring into the building. The store has reddish-stained wooden flooring and mustard-colored walls. There's no need for the simplistic signage that men are presumed to require. And yet, Pearlstein is struck by the number of men who see her store and ask why no men's shops look this interesting.

"I have not seen a men's store that I would want to emulate," she says. "I would love to see one that was unintimidating, comfortable, modern but not hip, and easy on the eyes -- different, but not ridiculous."

Pearlstein has much more fun buying for women, "especially in that gray area that's not really business wear and not really play wear. Men have a very hard time with that," she says. "My brother works alone and he said he gets up every morning and wears a suit and tie anyway. I took him to a store and showed him a soft jacket and he said, `Is that a woman's jacket?' "

There is no confusion about gender at James, a high-end men's shop with branches at Montgomery Mall and Tysons Galleria. James is a classic men's store -- lots of wood; impeccably dressed, authoritative salesmen. Italian designer suits line the walls. A couple of Argentine businessmen enter and buy four suits in a matter of minutes. Egyptian President Hosni Mubarak drops in and picks up a couple of pairs of Ferragamo shoes.

Michael Colen, who with his brother owns James, believes most men would be frightened away by a men's store that broke the rules -- the rich wood, the uniform of men's shop design. "It's a reflection of the clothes," he says. "You still wear white shirts and blue pinstripe suits, you still want your store to reflect the elegance of the classic clothes we sell."

At the high end, he says, knowledge about fashion has freed men to know designers the same way a woman might. "Fashion is everywhere now," says Colen, a short, broad-shouldered gent with jet-black, swept-back hair and quick, firm gestures. "Years ago, they wouldn't wear a curved spread collar. Now they will. They've been to Rodeo Drive and Worth Avenue. They know Via Montenapoleone," the main shopping street in Milan. Technology executives, foreign businessmen and other archons of the new economy are pulling Washington away from the old State Department, Brooks Brothers paradigm, Colen believes, and at least in the world of $2,000 suits, men are learning to enjoy shopping.

To a point. Yes, Colen has a customer -- a prominent local lawyer -- who uses shopping the way many women do, as a stress reliever, dropping in whenever he's working on an especially tough case to drop a few grand on new threads. But a significant number of Colen's customers are still men for whom shopping is a chore, men who make an appointment so they can get fitted and out before shopping panic sets in.

Immediately next door to James at Tysons Galleria, the Colens also own a Versace Jeans Couture shop, which is managed by Michael's wife, Lisa. The Colens wanted their Versace shop to look as different as possible from the men's store. They wanted the Versace to be common ground, a place where men and women coexist. And it is, with a cobblestone floor, eye-catching china decorative pieces and an overall image of chic black. But even here, Lisa Colen has concluded that shopping remains far more important to women -- both as a form of social discourse and as a way to define oneself. She says her customers are mostly "the women who don't work, women who go to lunch at Neiman's. They're constantly asking when the new goods are coming in. Men haven't picked that up yet. Society just isn't geared that way. Look at any newsstand: There are 50 women's fashion magazines and then there's GQ."

All those magazines, along with the rhetoric of women's liberation and the changing work force, have contributed to a powerful shift in the very notion of fashion. As Teri Agins writes in a new book, The End of Fashion, the industry's emphasis on urging women to create their own "individual style" has backfired. Women were told they could do as they wished, and they really did. No longer would they blindly accept the dictates of the fashion fascists of Seventh Avenue. Prices and sales have drooped throughout the '90s. The advent of Casual Fridays and the general loosening of standards throughout society devastated the fashion industry. "The more confident and independent women became, the less they liked to shop," concluded a study by a New York ad agency. "The more they enjoyed their work, the less they cared about clothes."

So farewell to Garfinckel's and Woodies and many of the traditional foundations of retailing. Marvel instead at the ever-expanding Gap empire -- Banana Republic, Old Navy and their many imitators: clothing for the anti-fashion generation, casual, barely affected by the seasonal whims of snobby designers. But what does this mean? Will the Gap generation -- the late boomers on down to Gens X and Y -- grow out of its casual style, or are we witnessing a genuine change in who we are and how we dress ourselves?

Gapwear is generic, classless, easy, but most of all it is unisex. "Almost every man has had the experience of shopping a certain part of the store and then realizing oops, you're in women's -- and the other way around," Underhill says. "That's part of the evolution in our culture."

Of course, even at the Gap, women are the focus. Enter the store, and the women's stuff is almost certain to be on your right, because we're wired to look to the right, and so that's where you put the important stuff. Underhill and I walk into a Gap at Short Hills Mall in New Jersey -- as good a place as any to examine the species Shoppus americanus in its native habitat -- and sure enough, there are 26 women on the right side of the store, one woman

on the left. Not a man in the place on this Saturday afternoon.

On to Abercrombie & Fitch. Here's a place with an image so muddy that for years I thought they sold knives and guns. Turns out they've retooled themselves into the cutting-edge expression of Generation Y shopping culture, which is to say, they have made a mint selling T-shirts to young men and women in a store that looks like a suburban kid's fantasy of a 1950s men's club -- lots of wood, dark plaid carpeting, galvanized steel buckets to hold sandals, chandeliers of faux deer antlers. No salesperson approaches us; no one will even make eye contact. The "greeters" stand in front of the store playing hacky sack with each other, ignoring customers. Kids pour into the place. Gender, shmender.

"I'm glad I'm 47 and not going to be around in 100 years, because I don't know what's going to happen to my gender," Underhill jokes. But he is serious: He believes some kind of convergence is happening between the sexes. The relationship between gay men and straight men, while still tense and sometimes antagonistic, is easing. And less conservative, more European clothing -- which many straight men would once have avoided because it might raise questions about their sexuality -- is now worn without fear.

Some believe the young generations will come back to old shopping habits simply by virtue of growing up, getting good jobs and finding mates. Underhill has a theory that the Gap generation has bought into wearing "uniforms," in this case the upscale T-shirt, and will, like generations before it, grow into wearing "costumes," more individualized looks made possible by high fashion and its mid-range knockoffs. "Gen X is now going to Ralph Lauren and they want those Purple Label, $1,800 suits, but they will soon learn that for the same money, they can have a suit custom-made and it will actually fit," Underhill says. He foresees a future in which women and men alike are lured into shops that provide more tactile sensations, more entertainment, more clear information, more reasons for men to feel welcome and curious.

Michael Colen wraps himself in the belief that unisex casual is a passing phase. "A guy doesn't want to look like his father, and then he grows up, and he does want to look like his father," he says. "Even if they're not going to get dressed up, they will want a more sophisticated kind of sportswear." Or so he hopes; James's customers have always tended toward middle age, but Colen concedes, "We don't get as many young as we used to."

Concerned menswear makers are trying to jump-start that transition away from Gapstuff and lure men back to suits and ties with ad campaigns about how much fun it is to dress up. But most men's retailers evince little evidence of being ready to deal with a generation that has broken away from traditional patterns.

"It's a Catch-22," Nancy Pearlstein says. "The men aren't changing because the retailers aren't changing, and the retailers are afraid to change because men remain afraid of change."

Peter Marx, the Saks Jandel president who started out selling menswear at Britches of Georgetowne 20 years ago, believes men's shops may yet be forced to become more like women's -- more distinctively designed, more attuned to the individual. "There's been a belief that men don't notice, men don't care," he says. "But as things heat up -- and it won't happen in Washington first, Washington is not the ultimate for men's business -- you will have to spend more on aesthetics."

New store designs -- and some are coming, with Saks Fifth Avenue planning an all-men's store at the renovated Mazza Gallerie -- will have to compete not only with traditional shops and catalogues, but with online sites, which are starting to become a major factor in clothing sales. The most starry-eyed of retail futurists argue that we are at the dawn of a new age of convergence in gender shopping roles. They think the anonymity of e-commerce will liberate men to do more of the shopping, to indulge their fantasies without fear of being judged less masculine.

Across the gender divide, some cybernauts believe that clicking for clothes may prove so easy that the 20th-century model of shopping as therapy and social activity for women will simply drift into oblivion. Moody suggests that the Internet might help women realize that, despite a lifetime of cultural cues to the contrary, "they, like men, really don't like to shop."

Hardly likely. While the initial read on online purchasing behavior lent some credence to such grand notions of social change, tradition once again is emerging triumphant. Old-fashioned stores will be with us always, Underhill insists; after all, women (and maybe men, too) want to touch. But online clothing sales, which jumped 600 percent from 1997 to 1999 and anticipate continued dramatic growth, will be another element in the mix.

In the first couple of years of online shopping, men bought about half the clothing sold. But the traditional 70-30 break in favor of women doing the shopping is asserting itself online, especially as the second wave of Web sites have taken on a considerably more feminine look and approach. The Brooks Brothers and Jos. A. Bank sites, for example, include little more exciting than "Worsted Wool Gabardine Trousers, $79.99," with a dull snapshot. Over at womenswear sites such as lanebryant.com, it's fantasy and image all over again. You can buy clothing, to be sure, but it's all mixed in with palm readings, horoscopes, "steamy summer videos," swing songs, poetry pages and chats about sex. The more things change . . .

Marc Fisher, who writes the Potomac Confidential column in the Magazine, is special reports editor of The Post.