The only time filmmaker Robert Greenwald ever shopped at what is now the planet's largest chain store, he bought a basketball. The purchase, about two decades ago, serves as a fitting metaphor for the subject of his latest documentary, Wal-Mart: The High Cost of Low Price. "That was a really lousy ball," he points out, during a telephone interview from California. "It wouldn't hold the air."

The big-box retailer, with headquarters in Arkansas and 5900 outlets worldwide, reported $285.2 billion in sales last year. Greenwald's 95-minute expose screens at more than a dozen Vermont sites beginning November 13. It contends that this success comes at the expense of an oppressed workforce and devastated downtowns.

"They burn and pillage," says Greenwald, 60. "It's a question of how much power we allow corporations to have."

Wal-Mart CEO H. Lee Scott, Jr. earns $28 million a year, or 897 times the average paycheck for his 1.6 million employees. About $4 million a day is spent to defend the company's reputation with ubiquitous TV ads in which "just plain folks" gush about how much they love their master.

Greenwald has recommended a more effective way to improve Wal-Mart's image: Spending that money on health care for the 53 percent of workers who are not covered and often dependent on Medicaid -- a category that includes 286 Vermonters. Instead, an internal memo leaked to the media last week outlines a plan to refuse jobs to anyone with medical problems.

The High Cost DVD is sold via the Internet to activist groups and for relevant house parties, the same grassroots marketing approach Greenwald used for previous docs he produced or directed: Unprecedented: The 2000 Presidential Election, Uncovered: The Iraq War, Unconstitutional (about civil liberties after 9/11), and Outfoxed: Rupert Murdoch's War on Journalism.

"These films are designed to be tools," Greenwald says. "People use them to organize, to change minds."

When not muckraking, he turns out movies for the big and little screen. Greenwald has been responsible for more than 60 productions over the years, including Sweet Hearts Dance. Shot in Vermont, the 1988 romantic comedy-drama features Susan Sarandon, Don Johnson and Bernie Sanders, then mayor of Burlington.

The U.S. Congressman, whose considerable star power was tapped once again for Outfoxed, is impressed with Greenwald's skills. "Robert is a very good friend of mine," Sanders says. "He's a pioneer in focusing on the most important issues and developing a distribution system that moves so quickly."

It's a mutual admiration society. "Bernie has been a leader in the fight for economic justice," suggests Greenwald, who's nonetheless proud that "all political persuasions" are represented in The High Cost.

He and his team of volunteers nailed down whistle-blowers, sought out ordinary people and visited a Chinese sweatshop that supplies Wal-Mart. "We wanted to tell human stories," Greenwald notes. "But I was foolishly naïve. I had no idea how difficult it would be to find people willing to go on the record."

The research was eye-opening. "I had no sense of the extent to which Wal-Mart destroys families and communities," explains Greenwald, a Manhattan native who says his psychologist parents "gave me a strong sense of right and wrong."

He majored in history at Antioch College and the New School for Social Research before immersing himself in the arts. "I started out off-off-off Broadway in a backstage capacity, then was elevated to directing plays in the mid-1960s," Greenwald says.

After relocating to Los Angeles for a theatrical gig, he was bitten by the film bug. "I started a production company. Anybody can call himself a producer out here," acknowledges Greenwald. His cinematic credits began accumulating in 1975. To date, he has 25 Emmy nominations and a Peabody Award.

Greenwald is most passionate about his topical projects. "The downside is, I'm totally exhausted. It's a wild ride to make these films and fundraise," he says, adding that his budget for The High Cost is $1.8 million. "I take no salary, so when the attacks come, it's not about paying my bills."

And the attacks have been plentiful, even before the release of his Wal-Mart epic. In August, Fox News commentator Bill O'Reilly compared Greenwald -- who is Jewish -- to Islamic suicide bombers and fans of Adolph Hitler.

Such nastiness only fuels Greenwald's zeal to foment social change. "Liberal ideas are in my family genes," he says. "A commitment to things above and beyond your own life is simply part of who we are."

Visit http://www.walmartmovie. com for more information about Wal-Mart: The High Cost of Low Price, or to find more than a dozen film showings in Vermont.