Two weeks ago, readers of the May 23 Wall Street Journal’s front page learned that 1.) slippers are now acceptable office wear in some New York companies and 2) Nordstrom, a retail chain, has requested piano players in its department stores to stop wearing tuxedos and dresses. The formality is apparently jarring to customers.

You would have to be a fashion cretin not to notice the casual dress trend that has swept through U.S. companies in the last few years, starting of course on the high-tech/dot-com West coast and moving most recently to East coast investment banks, consulting companies and law firms. In offices throughout the U.S. and abroad, three-piece suits and wingtips are morphing into more and more creative versions of casual, ranging from the aforementioned slippers to suits that can be worn as separates.

And there’s the wrinkle. Casual wear can be anything but casual. For some, it’s confusing; for others it’s anxiety-causing; for still others, it’s big business, provided they can stay one step ahead of the fashion curve. Furthermore, according to a new survey from the Society for Human Resource Management (SHRM) in Alexandria, Va., the trend may have hit a plateau.

From 1992 to 1999, says SHRM spokesperson Kristin Accipiter, companies reporting casual wear policies rose steadily. In 1992, 24% of the companies polled reported a casual dress policy either one day a week or every day; in 1995 71% reported casual wear policies and in 1999, 95%. The 2000 survey released in April, however, showed a total of 87% of its respondents reporting either a one-day-a-week or everyday casual wear policy.

Accipiter can’t explain the change, especially because casual dress in her opinion "has been an overwhelming success. It’s a benefit at virtually no cost to the employer." Many companies apparently have agreed. In the last few months alone, firms like Morgan Stanley Dean Witter, J.P. Morgan, Goldman, Sachs and Credit Suisse First Boston have instituted fulltime casual dress policies, joining companies like Coca-Cola, Ford, General Motors, Andersen Consulting and Sears, where casual dress in some cases has been the norm for years. (One hold-out is the federal government. Spokespersons at the White House and the FBI indicated that ‘business professional’ is still the policy.)

Knowledge at Wharton did its own survey on the subject, talking to a number of companies and consultants with opinions on casual wear policies. We also reviewed some of the fashion trends within casual wear, once it became clear that "dressing down" is subject to as many interpretations as "dressing up." Below we offer some observations:

FIRST, THE TERMINOLOGY: Casual wear is only one of the phrases used to describe the trend away from pinstripes and high heels. Other terms include "business casual," (usually means the dockers-khakis-polo shirt look), "business appropriate," (a step-up from casual), "business ready," (meaning you must have a ‘traditional’ suit ready to wear at all times) "corporate casual," "clearly casual," "resort casual" (definitely not allowed in the office), "refined casual wear" (acceptable provided you know what it is) and perhaps, most appropriately, "casual confusion."

DOs AND DON’Ts: At least on the East coast, guidelines call for clothes to be "in good taste." No to denim, spandex, jeans, team logo shirts, shorts, halter tops, tank tops, leggings, sweat suits, warm-up suits, and provocative or revealing clothing of any kind. No also to moccasins and sandals. And generally no to t-shirts, except that a recent newspaper article reported on t-shirts’ new-found versatility, at least among Manhattan shoppers. For women, t-shirts are trendy and inexpensive, and the more upscale versions are showing up in offices.

CASUAL WEAR BACKLASH? Some firms are opting to return to a more formal look, with several East coast firms actually contemplating a "Dress-Up Thursday." Beverley O’Connor, administrative office manager for headhunter Korn/Ferry’s Chicago practice, says that her office "doesn’t have an official policy but that many of the employees opt to wear formal business clothes. We have to trust that people understand they should wear what is appropriate. In a professional services environment, that tends to be business attire … I think more and more companies are going that way. They have experimented with casual wear and in some cases have found it hard to instill in employees an idea of what is suitable" for the workplace. Ann Pasley-Stuart, a consultant in Boise, Idaho, doesn’t believe a casual dress policy is good for all organizations. "In some companies with a casual dress policy we see more and more casual attitudes and sometimes even a deterioration in work behavior. Employees just kind of kick back and things like customer service can suffer. Some companies have gone from casual Friday to fulltime casual and then back to casual Friday."

THE NEW NEW SUIT: While some fashion-conscious types consider suits old-fashioned, anti-technology and definitely not cool, others are redefining the suit’s look and reputation. Scott Omelianuk, executive editor of Esquire magazine and author of a book called Work Clothes, offers this opinion: "We have a philosophy here where you should never use the words ‘dress down.’ In fact you should never dress down. You should seek to dress up, just do so less formally than you might have in the past. Putting on a pair of khakis and polo shirt is in some respects a great all-American look. But it does nothing to distinguish yourself … There is a certain amount of snobbery involved, because if you can put together a really great informal outfit, you are suggesting that you are more creative or more interesting than someone who can only think of a polo shirt or a pair of dockers … Some people are going back to suits, because they like how they look. There is nothing wrong with that. I wear a suit to work every day, sometimes with a tie, sometimes without. The suit becomes, instead of a uniform, a personal choice … In our August issue we have a special package on ‘the new suit.’ It’s different. It lacks padding, it’s lightweight, it doesn’t have a lining. The silhouette is nicer. It’s softer and more comfortable. So more and more people who don’t necessarily wear suits will start wearing them because they’re cool."

FASHION AS STRATEGIC TOOL: Here are the reasons some firms give for going casual: 1) to be more like their high-tech clients where casual dress has been the norm since the 1980s; 2) to give them an edge in recruiting and 3) to improve productivity … On the client issue: "In addition to business casual being the prevailing attire for emerging growth and high tech companies, it’s the prevailing attire for very traditional clients as well, such as utility companies," says Howard Meyers, managing partner in the Philadelphia office of Morgan, Lewis & Bockius, which went casual this spring. "You begin to wonder, really, why am I dressing up? We had casually-dressed clients tell us that they wanted the lawyers who met with them to be dressed casually as well …" On the recruitment issue: While the Coca-Cola Company doesn’t see its casual wear policy specifically as a recruitment tool, "I do think it is an advantage in terms of attracting young people," says Coke spokesperson Robert Baskin. "The economy is so excellent today that anything that helps you attract talent is worth doing." One reason for Goldman, Sachs’ casual wear policy, says a spokesperson, "is so that people can focus on their job and not on what they have to wear." In addition, it makes the company "an attractive place to work…" On the productivity issue: Esquire’s Omelianuk definitely doesn’t link casual wear to increased productivity. "One of the reasons some companies went to fully casual instead of one-day-a-week was they found that people were completely unproductive on Fridays and thought of that day as the adult equivalent of a field trip … I don’t think casual wear makes people more productive. If you are an unhappy person and/or work in an unhappy environment, that won’t be affected by a dress policy. If that were the case, Prozac wouldn’t be such a successful drug. We would just change our clothes."

IMAGE-BUILDING: Of course casual wear is nothing new even at companies like General Motors where many of the manufacturing divisions have always dressed casually. "The supervisors used to wear ties but that wasn’t seen as promoting a team approach so about 10 years ago they went to polo shirts," says spokesperson Kathy Tanner. About five years ago a casual wear policy was instituted in GM’s front offices in order to promote more of a culture change, and to show that the company is "not a staid, formal organization but one that moves quickly and is collaborative." Apparently the policy is popular. "If someone came in wearing a coat and tie who normally didn’t wear one," says Tanner, "the question he or she would immediately be asked is, "are you going on a job interview?"

PUTTING IT IN WRITING: A lot of firms don’t have guidelines for casual wear. "This is really dictated by common sense," says Coca-Cola’s Baskin. The company instituted a casual wear policy earlier this year. Like almost every firm we talked with, Coke employees still dress formally in meetings with, for example, non-dot-com customers, business partners and/or certain senior managers. "The policy was designed to give people an option in terms of how they wanted to dress, whether that’s business casual or more formal. It’s a recognition of the changes in our society, of the fact that most organizations have become somewhat more informal in terms of dress." Other firms do have guidelines: A New York law firm specifies shirts with collars and buttons, and requires socks at all times for men; no jeans or sneakers, and no halter and tank tops (for women). At Ford, guidelines state that business casual is not mandatory and that traditional business attire continues to be appropriate for all workdays. The guidelines specifically define the difference between casual and business casual. "Casual is what you might wear to social gatherings away from work like a picnic. It’s more relaxed than the type of clothing expected in the workplace." Pasley-Stuart recommends strict guidelines on what is appropriate dress and what is not. "Banks, law firm and health care companies allow a relaxation of dress codes and then they’re surprised when someone comes to work dressed inappropriately. Dress codes need to be set up and monitored for a casual wear policy to succeed."

BLACK AND BROWN IN SINGAPORE: Globally speaking, it’s a mixed bag. As far as Coca-Cola is concerned, it’s up to the managers in each country to set the dress code. Some Coke offices are still somewhat formal; others have been doing business casual for some time … Morgan, Lewis & Bockius’ 12 offices (and 1,050 attorneys) around the U.S., Europe and Asia are encouraged to adopt business casual. "I am told anecdotally that our English lawyers in London have not taken as readily to business casual as people in the U.S.," says Meyers. "But then I’m reminded of the story that the British themselves started the concept of casual Fridays in the 19th century when they wore tweed suits to the office on Fridays because they were leaving on the afternoon train for their country estates …" At Ford, employees who travel overseas on company business are asked to call ahead to find out if business casual applies … An article in a Singapore newspaper goes into considerable detail as to what’s appropriate casual wear in that country. On the subject of men’s socks alone, it offers three directives: "Wear them; wear them in any color but white; never wear blue socks with brown shoes – Americans and Britons detest this color combination so you may offend your clients from these countries."

CASUAL WEAR IS BIG BUSINESS: At Morgan, Lewis & Bockius, partners brought in Macy’s, Nordstrom’s and Joseph Banks clothiers to give seminars, and discounts, on casual wear to the firm’s employees. The New York law firm of Cadwalader, Wickersham & Taft put on a fashion show led by Polo/Ralph Lauren after also making the switch. General Motors works with local department stores to offer casual wear fashion shows at lunch time. Stores like Brooks Brothers, Lands’ End and Barney’s are offering more modernized versions of suits that in some cases consist of separates that can be mixed and matched for different looks. New styles of casual wear include silk knit shirts, flood pants, camp shirts, cropped pants, embroidered tops, safari shirt-jackets, and the just-launched Regis Philbin ("Who Wants to Be a Millionaire?" host) line: shirt and tie in the same dark color.

IN THE END, AMBIGUITY AND ANXIETY: Employees accustomed to putting on a dark suit, dress shirt and lace shoes (for men) or suits, skirts, blazers and high heels (for women) suddenly have to worry about their attire. "Now it’s what kind of slacks, what kind of shirt, what’s acceptable and what’s not. The ranges and limits are tested and they are a lot more ambiguous," says one ambivalent convert to casual wear. In other words, it takes considerable thought and confidence to dress well casually. Then there is the question of how to distinguish yourself in a workplace where you want to be casual, but don’t want to look like the person two floors below who makes one-third your salary. Finally, most people would admit that business wear is generally more flattering than other styles. Suits and dresses hide a multitude of imperfections that just don’t get covered up by most casual wear. "People look good in suits," says Esquire’s Omelianuk. "They have pockets to keep things in. You get better service when you wear one. They can take you anywhere you want to go."