A few months ago, I attended what can only be called a "green Tupperware party." While sipping sangria and munching on organic plum tarts, a dozen women got advice on how to make our lives more environmentally sustainable. We passed around samples of earth-friendly products available for purchase, from biodegradable bamboo towelettes to recycled plastic compost bins.

EmagineGreen, the organizer of these eco-fiestas, believes we need more practical advice about sustainable living and more products. Given the vocal environmentalism of so many prominent retailers, this 1950s approach seems ironic. Can't people be green consumers while shopping at their favorite stores? I spent several weeks trekking from shopping plaza to shopping plaza searching for signs of environmental responsibility. It wasn't long before my excursion became a sad and lonely endeavor.

My first stop was Wal-Mart. Between CEO Lee Scott's public pronouncements about his commitment to sustainability and the company's success with compact fluorescent lightbulbs, I figured there had to be lots of choices among the zillions of products. So when I got there, the lack of staff training and education about green products was shocking. I inquired about low-VOC paints. "Low what?" said the paint clerk. Over in the gigantic apparel department, I asked an associate if the store carried organic cotton. "I have no idea," she said. Three associates later, we unearthed some 100% organic-cotton T-shirts on clearance left over from Earth Day.

I got an even ruder surprise at the Gap. The company hails its membership in a group called the Better Cotton Initiative and has vowed to stock clothes made from organic cotton and other eco-materials. My local Gap, though, had only regular cotton. Kindley Walsh Lawlor, head of strategic planning and environmental affairs for Gap Inc.'s social-responsibility team, claims that there's only enough organic cotton in the world to fill "one large shipping vessel."

My simple advice to retailers is that if you're touting it, stock it. Toys not made with harmful chemicals should be easy to find in the wake of last year's recalls. Indeed, in March, Toys "R" Us introduced an eco-friendly line of cotton stuffed animals, organic-cotton dolls, and unpainted wooden and recycled-plastic toys. Yet at the Westminster, Colorado, Toys "R" Us, my greeter didn't have a clue where to direct me. Eventually, the store manager located some of the toys hidden on a shelf at the end of an aisle.

This all adds up to a squandered opportunity to educate millions of shoppers about the value of green products. What's the point of saying you carry green products if you don't know how to sell them? Wal-Mart cleans up on sales of organic milk and natural cleaning products. That's because those items are clearly understood by customers to be healthier and safer. "It's all about the benefits of the product," says Laurie Demeritt, president and COO of the Hartman Group, a consumer-research firm. "Is this going to be good for me and my family? It's fairly self-serving."

For some reason, though, retailers haven't figured out how to inspire customers to buy, say, organic cotton. It's bad marketing. If consumers knew how many chemicals it takes to grow and manufacture conventional cotton goods -- how it affects our water, food, air, and our risk of cancer -- maybe that would change. In a crowded marketplace, it is an unexploited competitive advantage.

Persuasion is corporate America's greatest renewable resource. If retailers can't harness it for good, see you at the next green Tupperware party.