(FORTUNE Magazine) – Five years after retiring as CEO of Philip Morris Capital Corp., George Lewis sits in his Stamford, Conn., home, taking in the lush view and reflecting on his arduous path to the top. His conclusion might surprise you. "I had a great career, a great career, and I was very fortunate," he says. "But if I were coming along today, I probably would step out and become an entrepreneur."

Lewis is not the only one questioning whether corporate America is the surest avenue to success and power these days. A generation after Lewis and his five fellow trailblazers fought their way to the top, there's a whole new world of career possibilities that simply don't require scrambling up the slippery corporate pole. Take Silicon Valley, where Indian, Chinese, and other Asian entrepreneurs have been achieving the kind of wealth typically reserved for the uppermost pay grades of the FORTUNE 500. "Sure, your company may never be as big as GE, but there's more to gain in pay and personal satisfaction," says Sridar Iyengar, president of TiE, a global support network for Asian entrepreneurs.

Granted, corporate America is no longer the stone-cold racist nightmare it once was--three African Americans currently hold down the top spots at FORTUNE 100 companies, including Richard Parsons, who took a winding path from attorney at a New York City law firm to CEO of publicly held Time Warner (parent of FORTUNE). But that doesn't mean everything's just exactly perfect in the executive suite. And since hanging out one's own shingle is more attractive--and lucrative--than ever before, retaining talent has become a real challenge for big companies. Sure, corporate America has been downsizing, but no company wants to lose talented people--least of all talented people of color who have the added potential of helping corporations compete in a multicultural world.

But as it happens, people of color are precisely those most likely to leave the corporate world. A recent survey of employees with graduate degrees by the Ewing Marion Kauffman Foundation found that 26% of African-American and 20% of Latino male respondents were considering leaving their jobs to start their own businesses, compared with 11% of white males. Hewitt Associates, the big consulting firm, has been tracking a disproportionately high attrition rate among minority groups. Though hard numbers are difficult to come by, Hewitt calls it the "revolving-door syndrome."

What's troubling about the revolving door is that it's not just the lure of startups drawing people out: After all the progress and all the money spent on diversity programs--as much as $80 billion over the past ten years, by some estimates--many people of color still don't feel welcome in corporate America. A recent Hewitt survey found "minority employees to be less engaged than their white counterparts due to feeling isolated and excluded. When these concerns reach a peak," the report concluded, "minority employees leave the organization."

The problem isn't overt racism as much as an array of subtle barriers and burdens, most unintentional: The manager who doesn't invite Miguel for a round of golf because he assumes Miguel doesn't play. The boss who evaluates his team based on the ability to bring in new clients but never considers that client bias may put minority staffers at a disadvantage. And the African-American VP whose regular job gives him more than enough to do but who is "asked" to sit on every diversity roundtable and conference, and to mentor every new minority hire. It's not just alienating. It's exhausting.

There are some reassuring signs that corporate America is starting to get it. More than 75% of the companies in the Hewitt survey see the need for enormous change in their inclusion policies and practices. If the focus evolves from recruitment to retention and promotion, the revolving door may not look quite so attractive.

Change will come, if for no other reason than that it's a bottom-line issue. When it finally does come, how will we know? Well, for one thing, we won't need to run any more lists of influential people of color.

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