"He has been too benevolent," she said. "He's right that a happy employee is a productive long-term employee, but he could force employees to pick up a little more of the burden."

Mr. Sinegal says he pays attention to analysts' advice because it enforces a healthy discipline, but he has largely shunned Wall Street pressure to be less generous to his workers.

"When Jim talks to us about setting wages and benefits, he doesn't want us to be better than everyone else, he wants us to be demonstrably better," said John Matthews, Costco's senior vice president for human resources.

With his ferocious attention to detail and price, Mr. Sinegal has made Costco the nation's leading warehouse retailer, with about half of the market, compared with 40 percent for the No.2, Sam's Club. But Sam's is not a typical runner-up: it is part of the Wal-Mart empire, which, with $288 billion in sales last year, dwarfs Costco.

But it is the customer, more than the competition, that keeps Mr. Sinegal's attention. "We're very good merchants, and we offer value," he said. "The traditional retailer will say: 'I'm selling this for $10. I wonder whether I can get $10.50 or $11.' We say: 'We're selling it for $9. How do we get it down to $8?' We understand that our members don't come and shop with us because of the fancy window displays or the Santa Claus or the piano player. They come and shop with us because we offer great values."

Costco was founded with a single store in Seattle in 1983; it now has 457 stores, mostly in the United States, but also in Canada, Britain, South Korea, Taiwan and Japan. Wal-Mart, by contrast, had 642 Sam's Clubs in the United States and abroad as of Jan. 31.Costco's profit rose 22 percent last year, to $882 million, on sales of $47.1 billion. In the United States, its stores average $121 million in sales annually, far more than the $70 million for Sam's Clubs. And the average household income of Costco customers is $74,000 -- with 31 percent earning over $100,000.

One reason the company has risen to the top and stayed there is that Mr. Sinegal relentlessly refines his model of the warehouse store -- the bare-bones, cement-floor retailing space where shoppers pay a membership fee to choose from a limited number of products in large quantities at deep discounts. Costco has 44.6 million members, with households paying $45 a year and small businesses paying $100.