(FORTUNE Magazine) – For millions of Americans, the workplace is like some nightmarish schoolyard--a place where bosses shake down subordinates for their psychic lunch money and then stomp on their egos for sport. So contends Columbia University psychologist Harvey Hornstein in this disturbing new study of managerial abuse, Brutal Bosses and Their Prey (Riverhead Books, $19.95). Working from questionnaires filled out by nearly 1,000 men and women over an eight-year period, Hornstein estimates that 90% of the U.S. work force has at some point been subjected to abusive behavior. He adds that on any given day, one of five people gets abused by a boss.

The problem here, and it is a substantial one, is just how one defines boss abuse. We hear from some alleged victims who seem a bit thin-skinned. One woman falls apart because her boss turns his back on her during a meeting; one man is ready to kill because his boss takes credit for the work of underlings. Bosses can clearly be rude and egotistical without crossing the boundary into abuse.

But the book does effectively document the spread of some undeniably monstrous behavior--sexual harassment of the crudest sort, verbal and physical threats, lying, deviousness, and all manner of inhumane acts. Hornstein spends a few pages delving into just what motivates the abusers; he blames some of the worst sins on pressures from the seemingly endless restructuring of recent years.

IN THE END, however, he clearly has scant sympathy for supervisors who become brutish: "Feeling powerless, they enforce their power over others; feeling frightened, they explode, piling abuses on their frightened subordinates; feeling small, they belittle others in the futile hope that it will make them appear big." If that sounds like someone you have worked for--or someone you face in the mirror each morning--you will probably recognize at least one of the six types of nasty bosses Hornstein lists. Dehumanizers like to transform subordinates into faceless victims. Blamers treat workers like wayward children. Rationalizers justify abuse by focusing on some greater corporate good. Then we have Conquerors, obsessed with demonstrating their personal power. Performers try to make their own work seem more important by denigrating that of others. Manipulators, a particularly unpleasant breed, tend to "waffle, dancing to and fro on the periphery of an idea, until the matter's success or failure becomes clear."

All this boorishness, Hornstein emphasizes, is not without cost. Companies that harbor abusive managers may face a range of lawsuits and will certainly be left with a shell-shocked, less productive work force. Employees who are victimized take a bigger hit; many, says Hornstein, regularly suffer from anxiety, depression, heart problems, gastrointestinal disorders, headaches, skin rashes, insomnia, and sexual dysfunction.

The most compelling moments are the first-person narratives of the victims themselves. A woman executive talks of a boss who bullies underlings into submission at every meeting: "He believed that subordinates had no right to engage in free thought. He actually said to others: 'Disagreement is disrespect.'" A man talks about his supervisor's cracking under the pressure of a downsizing: "He was awful to everyone, literally throwing work at us. And he'd mutter about how stupid, sloppy, and incompetent we were."

In one of his most distressing discoveries, Hornstein details how technological advances have provided some wackos with new methods of tormenting their hapless employees. Intrusive electronic surveillance is on the rise, and some nut jobs have grown fond of "flaming"--sending rabid threats or crude comments to workers via E-mail.

In recent years, Hornstein points out, violence has increasingly been the ultimate result of flagrant managerial abuse. He zeroes in on aspects of the U.S. Postal Service that may have contributed to several bloody incidents: "Employees...reported problems with their bosses, characterizing them as unfair, infantilizing, autocratic, and even physically abusive. They said that electronic surveillance systems monitored and controlled behavior in ways that crossed the boundaries of reason and respect...There was no trust." Ominously, this book makes clear that such conditions--and the enormous pressures they produce--are not all that rare these days.

Hornstein is weakest when he lists several simplistic methods abused workers might use to survive. Recognize the sins bosses commit and know the abusers for what they are, he advises. Be alert for unwarranted behavior from on top, and reach out to others who are being abused. Even though most abusers won't benefit from counseling, he says, it might be worthwhile to suggest they seek it anyway. Only Hornstein's final admonition may do much to halt the circle of abuse. Even if you are being victimized, he says, make sure you are not brutalizing your own subordinates.