Fake. Fraud. Phony. The words echoed in her head.

When Joan Harvey decided to try graduate school after years of motherhood, diapers and "Sesame Street," she feared that other grad students were smarter than she was. She was certain her lack of academic training in her field, psychology, would keep her at the back of the class.

Harvey decided to act as if she knew as much as the others. "I began to feel I was a fake," she recalls. Overcompensating in her studies, Harvey meticulously prepared assignments to eliminate flaws she thought could expose her as a fake. It would be only a matter of time, she figured, before she'd be discovered and branded: Impostor.

Now a Philadelphia psychologist and clinical associate at the University of Pennsylvania's School of Medicine, Harvey maintains that a majority of successful Americans -- as many as 70 percent -- suffer at least mild symptoms of the Impostor Phenomenon (IP). Some are so stricken with feelings of fraudulence, she says, that they become professionally crippled, displaying anxiety symptoms that range in severity from butterflies in the stomach, tension headaches, sweaty palms and diarrhea to psychosomatic panic and tranquilizer abuse.

Who are the victims of IP? In her book, If I'm So Successful, Why Do I Feel Like a Fake? (St. Martin's Press, $14.95), Harvey writes that this psychological syndrome is selective in only one way: It "goes hand in hand with the idea of success. But that doesn't mean top-of-the-ladder, rich-and-famous kind of success. You don't have to be a world-famous movie star, corporation president or Nobel Prize winner to suffer from the feeling of being a fake . . . But you must have accomplished something about which to feel fraudulent."

Typically, she adds, IP victims share three characteristics besides some measure of success: A sense of having fooled other people into overestimating their abilities; attribution of their success to factors other than intelligence or ability or talent -- such as personality, luck, mistake or strings that were pulled; and a fear of being exposed as a fraud.

The very words of IP research -- fraud, success, fakery and anxiety -- are the stuff of the media spotlight. The issue has been tossed about on talk shows such as Phil Donahue's. And Harvey's book competes on bookstore shelves with Pauline Rose Clance's The Impostor Phenomenon: Overcoming the Fear That Haunts Your Success (Peachtree, $14.95), with other titles to follow. "I was asked by nearly every major publishing company in New York to write the book," says Harvey, explaining that she coauthored it after a New York Times story on her research prompted "almost half the people in New York" to call and confess they had IP.

But not everyone is buying it. Some critics brand the Impostor Phenomenon the real impostor -- and call it a bogus syndrome.

"It's hogwash -- a molehill made into a mountain," says Srully Blotnick. A psychologist and columnist for Forbes magazine, Blotnick recently published the results of a 25-year study that tracked the career development of 5,000 people in his book, The Corporate Steeplechase: Predictable Crises in a Business Career (Penguin, $7.95). He says he has seen little evidence of IP.

"It isn't there and we didn't encounter it," says Blotnick, who started the survey as a Princeton undergraduate in 1958. "We didn't even have 10 out of 5,000 who showed any signs of it -- and the ones who did experienced it temporarily. Instead of feeling like impostors, nine out of 10 successful people feel they're not getting enough attention for their success."

Other psychology and business experts are skeptical, too: If IP exists, they say, it isn't widespread. Howard Weiss, a Purdue University psychologist specializing in workplace behavior, says, "If I saw a good percentage of successful people with this Impostor Phenomenon, I'd be surprised."

"Millionaires -- and their moms don't love them?" exaggerates Paul D. McKinnon, a business administration professor at the University of Virginia's Darden School who says he hasn't seen "any people with this problem. I don't mean to discount what these people are saying, but I don't feel it's a pressing issue."

Edward B. Klein, a psychologist and visiting professor of organizational behavior at the Yale School of Management, says he has interviewed successful people who were afraid their pasts would catch up with them. "There are people who do have this feeling," says Klein. "But I haven't come across it very often."

Harvey's response: "Maybe they haven't been looking for it. People don't come to therapy with it as their chief complaint or problem. It's so much a part of their identity that they think it is unfixable and unchangeable. They don't even bring it up . . . You don't find what you don't look for."

But what attracts the most criticism is the contention that not only do sufferers hide IP, not only is it hard to recognize, but the syndrome can be so secretive that even its victims don't know they have it.

Known for their insatiable appetites for quickie diets and fitness fads, Americans also eagerly consume pop-psych syndromes. In recent years, the public has digested the Peter Pan Syndrome, the Wendy Syndrome, the Achilles Syndrome and the Superwoman Syndrome, to name a few. So saturated are we with neatly packaged, step-by-step instructions for mental aerobics that it's no exaggeration to say America suffers from the Syndrome Syndrome.

"We all are amateur psychologists and we just crave information on all of this stuff," says Peter Glick, a social psychologist at Lawrence University in Appleton, Wis. "So people who are popularizing things like this are trying to make a buck."

Harvey denies simple monetary motivation, but agrees that John Q. Public gulps down popular syndromes such as IP. "People do latch on to things," she says. "Maybe there is such a wide range of particular patterns or feelings that many people can latch on to it. If you write about something like this, it has almost a universal theme. Everyone can relate to it in one way or another."

Calling most pop psych "junk," Weiss stops short of applying the label to Harvey's work. But he says the appeal of a syndrome such as IP is also its danger: "It's the extent to which it simplifies everything and provides ready answers. In any particular book like this, there could be some truth, but the rate of utility of most of this stuff is pretty low. They overly simplify complex issues."

And oversimplification can lead to misdiagnosis that sidetracks the route toward resolving "real" problems. "If you slap the wrong label on it," says Blotnick, "you never get to the reality of the discomfort. You may have sweaty palms and diarrhea because you want to get to the executive suite and think you belong there -- not because you think you're a fake . . .

"In this country, you're supposed to be a success by age 35," he says. "Every ambitious person is in a hurry. This slaps a cheap, superficial label on anxiety that's more likely caused from being in a hurry."

Professional hypochondria might be a broader label for the flood of psychological aches and pains that seem to be accompanying growing anxiety in today's workplace. Blotnick says he hears almost all competent professionals use the phrase "running scared" to reflect not feelings of phoniness but the reality of their work -- namely, intense competition.

In IP's defense, Harvey says: "I never meant to imply that all anxiety comes from feeling like a fake . . . and nobody is saying it is a disease, or that it's pathological unless it reaches an extreme. A lot of people who felt like this have felt there is something wrong with them -- and that's the value. What I'm saying is that it is almost a universal feeling, a normal feeling or experience. It's saying, 'You are not crazy and you are not an impostor, either. You are not a criminal."

In fact, Harvey agrees with her critics who argue a little self-doubt is better than no self-doubt, especially in the workplace. Yet she is ambiguous on drawing the line that separates professional self-doubt from the mildest symptoms of IP. "It's all a matter of degree and balance," she says. "People are not supposed to know everything. But they're supposed to be realistic about what they don't know. It's the belief that you should know everything that's the problem."

Others are troubled that in the wrong hands, rather than being discarded as irrelevant, IP becomes a self-fulfilling prophecy, taking on a life of its own. But Glick says even that probably can't overrule an established work norm: We typically discount failure and take credit for success.

"People are inordinately arrogant and, in general, have high self-esteem," says Glick. "If anything, they tend to make errors in the opposite extreme -- especially people who are successful."

Blotnick agrees. He says that if his research has uncovered any syndrome among successful people, it's that they increasingly are disappointed in their achievements if they don't get the recognition and fame, too. He calls it the Celebrity Syndrome.

"We have a diet of the day, an exercise book of the week, and a syndrome of the month," scoffs Klein. "But why? There is a wish for the magic solution. But there are no magic pills that I know of."