"If you're going to come up with a practical solution to any problem," Paul Polak observes, "you have to first talk to the people who have the problem and listen to what they have to say. So that's what I did."

Psychiatrist Paul Polak was drawn to the problem of poverty while working with poor patients, and began his efforts in international development by talking with subsistence farmers in Bangladesh. They are among the world's one billion people who live in extreme poverty, which the World Bank defines as earning one dollar a day or less.

Polak has interviewed more than 3000 of these poor farmers, and notes, "They represent the vast majority of dollar-a-day people in the world. And everything we've done comes from what we learned from them."

One important lesson was that poor farmers need better tools to make their farms more efficient, so Polak established a non-profit organization called International Development Enterprises, or IDE, to develop and market cheap technologies. They include a drip irrigation system that uses plastic bags, tubes and the power of gravity.

IDE also produces a foot-powered pump, or treadle pump, for accessing ground water, which allows poor farmers to grow cash crops in the dry season, when they bring higher prices. He says the system quickly pays for itself. "It costs $8. Installed on a tube well, it costs $25. And when a farmer makes an investment, maybe part of that is borrowed, the average net return is $100 dollars after expenses in the first year."

IDE distributes the pumps through local businesses, providing an income for those who sell and install the devices.

Polak embraces a business model, and in addition to his non-profit work, has started a profit-making business to design and sell simple, practical devices in the developing world. He says poor farmers should be respected as business partners, not viewed as objects of charity, as they often are.

"A great deal of development aid is delivered as a gift," he says. "It's very clear from my experience that you can't donate people out of poverty. Poor people themselves have to invest their own time and money."

Polak's organization has sold one and a half million treadle pumps in Bangladesh alone. From Cambodia to Somalia, IDE sells simple drip irrigation systems and low-cost donkey carts. Polak says demand for these low-tech devices is immense, noting that there are 450 million farms of under two hectares in the world, but most agricultural tools and products are geared to big operations.

Polak has outlined his insights in a book called Out of Poverty, and it's required reading at the California Institute of Technology, where engineering professor Ken Pickar teaches a course on design for the developing world. Inspired in part by Polak, Pickar's class has teamed up with industrial design students from Landivar University in Guatemala to make products for poor villagers in that Central American country.

"The most successful one we've had recently has been a wheelchair which has been made by carving up bicycles," he reports. "They're actually able to form a very inexpensive sturdy wheelchair appropriate for a nation where people live on roads which are not very good, and where wheelchair substitutes right now in rural areas are basically putting people in a wheelbarrow, or allowing them to crawl through the dirt."

Several CalTech graduates have set up a non-profit company to manufacture and distribute the wheelchairs.

Pickar says his students look to Polak for inspiration, not to government or international agencies, as they tackle the problem of poverty in the developing world. "In development, most exercises of this nature are just that, they're exercises. They don't really result in any lasting value." He admits they may raise money and help donors feel good about themselves, but adds, "in terms of significantly improving the lot of people whose lot needs to be improved, the numbers of really successful folks, you can count on the fingers of certainly less than two hands. So when a guy is successful, you have to say, well, maybe he's saying something we should all listen to."

Pickar and his students are listening to Paul Polak. So are students in similar classroom programs at Stanford University and the Massachusetts Institute of Technology. And some graduates from each school have followed Polak's lead in designing products to improve the lives of the poor in developing countries.