“Clothing and grooming are the principle parts of one's appearance,” says Dixie Towers, Fashion Marketing & Management Instructor at The Art Institute of California — Orange County. “We are constantly judged by our appearance. Whether we think we should be or not is immaterial.”

What was once a look reserved for Fridays, business casual dress is now the norm for most office workers. A 2007 Gallup poll showed business casual was by far the most common work attire.

Of course, the type of industry and company heavily influences the type of dress. Predictably, business and finance companies typically incorporate a more formal dress code with computer and creative companies on the other end of the spectrum.

Some companies like Microsoft go so far as to encourage less formal clothing for employees and interviewees. A post by a company recruiter on the Microsoft Careers JobsBlog says: “The Microsoft dress code is all over the page and really depends on the division in which you work.” The poster describes dressing “nicely” as a button-down shirt and khakis, and advices against suits and ties. At Google, with its well-known casual environment, part of the corporate philosophy is “you can be serious without a suit.”

“Business attire is affected by the business you are in,” agrees Lydia Ramsey, a business etiquette expert and author of Manners That Sell. “But no matter what, there is a level of dress that the organization wants to maintain.”

Another factor is the degree of contact employees have with clients. Prudential, for example, requires business casual for workers, but raises the bar to “business attire” for those employees meeting with current or prospective clients. And as part of its dress code, Citigroup tells employees that “when attending business meetings with visitors or clients, your attire should reflect that of the individuals with whom you are meeting.”

There is good reason for that, Ramsey says. “If someone is not dressing up to the business climate and culture, they could be doing harm to the business itself.”

While Ramsey admits that the attire of employees without customer contact may not be as much of an issue, it still sends a message to coworkers.

“For the most part, it is noticed by others when someone is dressing out of sync,” she says. “Even if people don’t mention it or necessarily verbalize it, they’ll notice something is different about the person.”

The risk is signaling through casual dress that a worker’s position or function is not as important as others in the organization, Ramsey adds. It’s especially risky if most in the workplace are dressed more formally.

A more flexible dress code can be confusing for employees. General Electric’s dress code requires employees to “use good, professional judgment” and to “always select attire appropriate for a business office.” While those statements may seem open to interpretation, the code also lists items not to be worn including any type of denim, shorts, sneakers, and flip flops.

“If a company doesn’t have a ‘strict’ dress code, the employee at a minimum should dress for the job that is a level above their position,” advises Towers of The Art Institute of California – Orange County. “Even if a company has a very casual dress code, dress in a way that would inspire respect.”

For example, Towers says, a graphic designer should dress like an art or creative director. Such rules, of course, might not always apply since individuals can dress in vastly different ways. But Ramsey says it’s often appropriate to look to the organization’s senior people and mimic their attire.

“If you have aspirations to move up,” she says, “you need to follow their lead as closely as you can.”

According to Ramsey, the best way to avoid making a fashion faux pas in the workplace is to keep work and home wardrobes separate. That minimizes the risk of dressing too casually at work. The fashion-conscious employee doesn’t need to try to impress coworkers with a wide variety of outfits, she adds.

“Keep your personal wardrobe for your off time,” she says. “People at work don’t care that you come to work everyday in a new outfit.”