Across the United States, politicians and labor groups derided the company's health plans for their high expense and bare-bones coverage.

Two states, California and Maryland, even passed laws demanding, in effect, that the company spend more on employee health benefits.

"We want this giant to behave itself," one Maryland legislator, Anne Healey, said at the time.

The giant, it turns out, was listening. All the criticism was hurting its reputation and its ability to expand. So now, after spending two years seeking advice from everyone from Bill Clinton to executives at Starbucks, Wal-Mart is overhauling its health plans.

The company, according to data available for the first time, is offering better coverage to a greater number of workers. Wal-Mart, the largest private employer in the United States, provides insurance to 100,000 more workers than it did just three years ago - and it is now easier for many to sign up for health care at Wal- Mart than at its rival, Target, whose reputation glows in comparison.

Wal-Mart has hardly become a standard-bearer for corporate America: It still insures fewer than half its 1.4 million employees in the United States.

But the changes in its policies have accomplished what once seemed impossible. Many of its most ardent critics have put down their pitchforks. Andrew Stern, whose Service Employees International Union set up an advocacy group to attack Wal-Mart three years ago, now concedes that "there is clearly a focus on covering more people."

Given Wal-Mart's unparalleled track record of sharply cutting prices and wringing out inefficiencies, its focus on providing more affordable health care also holds significant promise in taming what has become a runaway expense in the United States.

In one sign of its success so far, the company has pushed down the price of 2,400 generic prescription drugs to $4 a month for employees, starting next year, a program that it offers, in more limited form, to its customers.

Now, the chain is even considering weight-loss clinics in its 4,000 stores and is toying with the idea of selling health insurance, hoping to finally bring coverage within reach of most Americans.

The company's turnabout demonstrates the power of public pressure to change even the biggest corporations like Wal-Mart, which has based its business strategy on low costs at all costs.

What Wal-Mart discovered was that the chorus of critics it had long ignored or blithely rebutted had a point. "We were spending a lot of energy, and we weren't making any headway," said H. Lee Scott, the company's chief executive, who once traveled the country defending the retailer. "Retrospectively now I say, yes, that plan needed to be improved."

For a company whose mantra is to pinch every penny, the improvements have not come without a struggle. For decades, tens of thousands of its employees were never eligible for coverage, and what was offered was too costly for a work force whose average wage amounted to roughly $20,000 a year.