(FORTUNE Magazine) – EVER WONDER WHY there are so few Asian Americans at the very highest levels of U.S. companies? It's certainly not for lack of education. The Census Bureau reports that 44% of Americans of Asian heritage are college graduates, way above the average (27%) for the nation. True, their numbers are relatively small, making up just 4.4% of the workforce. But Asian Americans are the fastest-growing minority in the U.S., having increased by 72% since 1990, vs. just 13% for the U.S. population as a whole. Moreover, according to human resources managers and recruiters, plenty of entry-level hires are of Korean, Chinese, Taiwanese, and Japanese extraction. Yet except for a scattering of luminaries like Avon CEO Andrea Jung, Asians are weirdly absent from high places. Only 1% of corporate directors are Asian. Even in Silicon Valley, where about 30% of tech professionals or their forebears hail from Pacific Rim countries, Asian Americans account for only 12.5% of managers; 80% of tech bosses are Caucasian.

So what gives? Jane Hyun, a former human resources executive at J.P. Morgan who now has her own consulting practice (see www.crossroadscareers.com), has written a fascinating book, Breaking the Bamboo Ceiling: Career Strategies for Asians (Harper Business, $24.95). It goes a long way toward explaining why Asian Americans aren't getting ahead in big companies--and what they can do about it. Hyun was born in Korea and grew up in New York City. Her family came to the U.S. when she was 8. "What many Americans don't understand is that people like me have one foot in two worlds," she says. "Of course I've assimilated, but I still feel Asian." And what does that mean? Ah. Hyun acknowledges that sweeping generalizations about any racial or ethnic group are tricky, because naturally there are always exceptions. Still, she points out that most Asians share certain cultural values, drummed into them since childhood, that are the precise opposite of what it takes to succeed in the corporate world these days.

One example: "Most Asians are taught from an early age to be self-effacing and to put the community ahead of one's own interests. Pacific Rim cultures are full of sayings like, 'The tallest nail gets hammered down,' " says Hyun. "So the idea of putting your ideas forward or marketing yourself or even taking credit for your own achievements--these are alien concepts." Asian Americans also have been taught to respect authority and defer to elders. "Often, in meetings, Asians will not speak up," Hyun observes. "Unfortunately, this reticence gets mistaken for aloofness or arrogance or inattention, when it is usually just the Asian habit of respecting authority. We wait for our turn to speak--and often our turn just never comes."

For those of us who sometimes wish our colleagues were a little less full of themselves, this doesn't sound so terrible. But Hyun's book offers a crash course in assertiveness for her fellow wallflowers. "The first step is self-awareness," she says. "Asian Americans may not know how we're perceived by our Caucasian peers and bosses, so we need to get honest feedback. This is why mentoring relationships can be so valuable, if you're paired up with a non-Asian mentor." If no one is willing to be candid with you about how you're coming across, she adds, then maybe you're working for the wrong company: "You'll never be able to deal with issues and problems that remain unspoken." Beware, too, of employers who offer training and development to "high potential" folks only. "The trouble is, How are they defining 'high potential'?" asks Hyun. "Do you have to look a certain way or act a certain way? To learn the skills you need to succeed, seek out companies that are interested in developing all their people, not just a chosen few, and that offer lots of opportunities for training, coaching, and mentoring."

Hyun urges people of Asian extraction to "practice taking the credit for your own work as well as acknowledging the contributions of others. You don't need to blow your own horn all the time, but train yourself to seize the right moments when they arise." And, while respect for those further up in the hierarchy has its place, try not to get carried away. Years ago, as a raw recruit in the HR department at J.P. Morgan, Hyun had to give a negative performance review to a high-performing manager with such lousy people skills that all his subordinates were quitting. "I was mortified. This person far outranked me, and he was 20 years older than I was. How could I go in there and criticize him?" she recalls. "I was so nervous, I stayed up all night preparing a script, trying to phrase everything extremely diplomatically. But in the end, the meeting actually went very well. I still don't like conflict, but after that, I found I could deal with it. You need to have those skills in your toolbox."

Affinity groups, those in-house organizations for employees of a given race or ethnicity, can boost Asian Americans' careers, Hyun says--"but only if they're not just social clubs. The group's activities have to be aligned with the company's larger goals." Increasingly, those goals are global. In companies expanding into Asian markets, "the Asian-American affinity group can act as a resource--developing best practices for reaching Asian consumers, for instance," notes Hyun. "That gives you a direct channel for communicating with top management." Never a bad group by which to be noticed--if you hope to join it someday.

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