For 12 years, Ann Kinder has sported a two-inch square tattoo on the inside of her left ankle. Because she regularly wears pants, many of her co-workers are hardly aware of the vibrant design, a peace dove styled in blue, white, green, and orange.

"I have colleagues with tattoos that are more visible," says Ms. Kinder, a communications associate for a nonprofit education agency in Naperville, Ill.

But no one can miss the nose ring Kinder added two months ago. "That's something I decided to be a little bolder about," she says, noting that several other women in her office have pierced noses.

Body art, once the province of bikers, longshoremen, marines, and punks, is going more mainstream, showing up in white-collar workplaces. As more young employees – both women and men – opt for ink and piercings, they face decisions about how much decorated skin to bare or not to bare. In the process, they are also quietly forcing their employers to accept them.

More than one-third of Americans between the ages of 18 and 25 have tattoos, and 40 percent of those between 26 and 40, according to a Pew Research study. For those over age 40, the number drops to 10 percent. In all, an estimated 30 million to 40 million people have tattoos.

As a further sign of growing popularity, reality shows on television, such as "Miami Ink" and "LA Ink," promote body art. Last week 7-Eleven even launched an energy drink called Inked, targeted to a rapidly growing niche market – young, tattooed Americans.

Fields such as entertainment and technology often permit relaxed dress policies. "I have clients who work all over the United States and are allowed to expose their tattoos," says Jamie Yasko-Mangum, a corporate-training consultant for Successful Style & Image in Orlando, Fla.

Other businesses remain conservative. "There are many professions where tattoos are not allowed to be exposed," Ms. Yasko-Mangum

says. These can include law offices, banks, restaurants, pharmaceutical firms, and insurance companies. In such places, women with butterflies and flowers decorating a shoulder or men with snakes and flame-breathing dragons encircling a forearm must rely on long sleeves to cover their art.

That's the approach David Kimelberg, general counsel for a venture capital group in Newton, Mass., takes to keep his tattoos a secret. "They do tend to be distracting," he says. "They're unique and colorful. Your attention goes to that if they're exposed."

Despite the secrecy, Mr. Kimelberg, who is also a photographer, found a network of heavily tattooed white-collar professionals. They form the subject of his book, "Inked Inc." Sixty percent of those he photographed are women.

After the book's publication in May, Kimelberg had to reveal himself to his company. To his relief, reaction was "quite positive," he says. "We pitch to start-up companies with pretty young management teams. [Tattoos] create a connection on a personal level. You're not seen as this conservative, stodgy group. They see you as more youthful. They can connect with that."

But many other employers and clients fail to make that connection. Despite the growing popularity of body art, some companies are clamping down.

"At first it was like, 'Oh, OK,' " says Brooks Savage, CEO of Executive Staffing Group in Raleigh, N.C. "But it has been taken a little too far. People are starting to tighten policies. I'm taking a stronger and stronger stand on it. I've had managers speak to employees." Some of his criticism is directed to young women whose shirts expose lower-back tattoos when they bend over or reach up.

Susan Potter Norton, an attorney with Allen Norton & Blue in Miami, also finds employers less willing to accept body art. "I've had a number of private-sector employers ask if they can require employees to cover up tattoos or decline to hire them," she says. The answer in Florida is yes.

Marty Kotis, president of Kotis Properties, a real estate development firm in Greensboro, N.C., does not have a strict policy against body art. For employees who do not interact with the public, where a good first impression is important, he takes a laissez-faire approach. His test is: "If it negatively impacts our business, it's not a good thing."

He interviewed one job applicant who wore a large nose ring. "I found it kind of distracting talking to her," Mr. Kotis says. "If a prospective client is sitting there and instead of hearing the pitch about our company is thinking, 'That must have hurt,' or 'Why would she have that?', that would be a concern."

Before Kinder had her nose pierced, she checked with the human resources director, who did not object. Kinder finds that the small ring has had "no negative effect" on her work environment. But a major fitness club where she holds a second job does not allow nose rings. She covers it with a band-aid while she works there.

Michelle Clark, creative director for a public-relations firm in Atlanta, keeps her tattoos concealed at work. "In the summer, I can't go sleeveless," she says. When she attends business meetings, she hides an infinity symbol on her wrist with a big bracelet. She also wears just one pair of earrings to work, despite having seven holes in one ear and three in the other.

"I prefer people to remember me for my work and not to be distracted by my tattoos or piercings," Ms. Clark says. "A friend insists it is her right to show off everything under the sun. She has a lot less respect in our business."

Even so, attitudes are changing, says John Putzier, author of "Weirdos in the Workplace: The New Normal." He describes the process as "more of an evolution than a revolution," adding, "Eventually, what's avant-garde today is more common tomorrow." He defends the right of managers "to regulate, dictate, and prohibit."

Mr. Putzier expects managers to evolve. "As baby boomers retire, Gen X and Gen Y will be doing the hiring," he says. "The standard of decorum for appearance will change and is changing." A shortage of skilled workers will also encourage companies to look beyond externals.

One heavily tattooed professional, Todd Dewett, is an associate professor of management at Wright State University in Dayton, Ohio. Although the stigma is softening, he says, most people still "stereotype anyone with a lot of ink." He adds, "The belief that tattoos will slow you down professionally in some fashion is not irrational." Mr. Dewett is the author of a forthcoming book, "Leadership Redefined."

Yasko-Magnum, the corporate-training consultant, advises those considering a tattoo to reflect on whether their profession will accept it. "When you are in an office, do not expose your tattoos, because you can lose your credibility. I hear people say, 'That's my personal expression.' But when you're working for a company, you have to conform."

She adds that she has seen clients, now in their 30s and 40s, who wish they had never gotten tattoos. That regret sends some professionals to dermatologists for laser tattoo removal.

In the long run, greater workplace acceptance will depend on whether tattooing is simply a trend or a lasting part of American culture, says Bob Kustka, a human resources consultant in Norwell, Mass.

For now, Clark takes a sanguine approach. "You have to take into consideration that not everybody likes what you like," she says. "You have to have some respect for what makes them comfortable and uncomfortable if you expect them to work with you."