t would be unfair to call "Nickel and Dimed: On (Not) Getting By in America," (Metropolitan Books, $23), by Barbara Ehrenreich, an extremely important business book.

To many people, the term "important business book" inevitably conjures up images of wonkish tomes studded with equations that rely heavily on the Greek letter sigma. And that bears no resemblance to this captivating account of Ms. Ehrenreich's attempt to survive on the kind of low-paying jobs that politicians think will provide needy women with an alternative to welfare.

The term "business book" also may deter some readers who most need the therapeutic shock of self- recognition that this book provides — those who run a waitress ragged with trivial demands and then leave a 5 percent tip; those who stare right through the office cleaning woman; and those who leave piles of rejected clothing in a Wal-Mart dressing room a half-hour before the 11 p.m. shift change.

So just promise that you will read this explosive little book cover to cover and will pass it on to all your friends and relatives, especially the ones who deplore what they call the general shiftlessness of the laboring classes, and we can forget about how to label it.

The concept behind "Nickel and Dimed" is deceptively simple. Prodded by Lewis H. Lapham, the editor of Harper's magazine, Ms. Ehrenreich made a blank slate of her impressive résumé — a widely published freelance writer, she is the author of "The Worst Years of Our Lives" and "Fear of Falling" — and set out to be hired at the going rate for unskilled labor. Her goal was to try to live on what she could earn in tight labor markets in Florida, Maine and Minnesota.

Ms. Ehrenreich does not insult us, or her temporary co-workers, by pretending that her experiment, undertaken over several months during the course of several years, actually duplicated what the working poor experience. Although the jobs she took paid $6 to $7 an hour, she was infinitely richer than her co-workers: "With all the real-life assets I've built up in middle age — bank account, I.R.A., health insurance, multiroom home — waiting indulgently in the background, there was no way I was going to `experience poverty' or find out how it `really feels' to be a long-term low-wage worker."

True poverty, she added, is "not a place you would want to visit for touristic purposes; it just smells too much like fear."

She permitted herself a car, a problematic luxury for most low- wage workers and one that allowed her to maximize her employment options. She drew the line at homelessness, personal danger and debilitating hunger, although she drew that line well beyond what many of us would recognize as tolerable.

But to an extraordinary degree, she walked the walk. She shouldered the burdens — trays of dirty dishes, a 14-pound backpack vacuum cleaner, 15- minute lunch breaks, and seven-day workweeks — that millions of American workers carry. She swallowed the righteous sermons she wanted to deliver to managers who demanded 10-hour shifts at straight time, in violation of federal wage and hour laws. She submitted to urine testing and crude "psychological surveys" to land a job. She worked until she was bone weary and then struggled to sleep in some airless and overpriced motel room — often the only shelter available to those who cannot muster a month's rent and a security deposit in the current drought of affordable housing.

On two occasions, she even sought help from charitable organizations catering to the working poor; somehow, she managed to remain polite in the face of the haphazard and utterly clueless assistance they offered.

And she talked to people, folks for whom her experimental life was the real thing. She looked beyond the bleak outer circumstances of their lives and saw the sometimes baffling and occasionally nearly sacred impulses that seemed to keep them going — pure grit, pride, teamwork, loyalty, humor and, of course, financial desperation.

Working for a cleaning service in Maine, she meets a woman who would rather keep working with an injured ankle than face her husband's wrath over lost wages. She befriends a teen-age Czech dishwasher in Florida who is little more than an indentured servant. She struggles to introduce the idea of a union to a shy worker at a Wal-Mart in Minneapolis while admitting to herself that she is just trying to enliven her own day with something resembling intellectual action.

There are times, it must be said, when Ms. Ehrenreich's political agenda and personal anger overwhelm her prose. Her fuzzy ambivalence about the politics of employing household cleaning help was especially surprising — working as a maid, she longed to be treated with dignity and respect, but she refuses to ever hire a maid herself, because she apparently cannot imagine the relationship being anything but degrading to both parties.

Nonetheless, it is intriguing to contemplate what American capitalism would become if every chief executive, every personnel director, every small-business owner — and heaven knows, every state and federal lawmaker — had to read this book. Or better yet, had to repeat Ms. Ehrenreich's experiment for themselves.