After a rocky beginning, the nonprofit group One Laptop Per Child thinks an advertising campaign will give a lift to the organization’s effort to place low-cost laptops in the hands of children in developing nations.

About 500,000 of the group’s light and rugged machines are being used in 31 countries, including Afghanistan, Cambodia, Ethiopia, Iraq, Lebanon, Peru, Rwanda and Uruguay. But the cost of the laptops, at less than $200 each, has been prohibitively high for many countries, and the number of laptops distributed has fallen short of early projections.

An additional 500,000 of these XO laptops are in transit or being built, and should be in use by early next year, said Nicholas Negroponte, chairman of the education and computing project.

The marketing campaign seeks to sharply increase those numbers. Television time, billboard space and magazine pages are being donated by media companies, including the News Corporation, CBS and Time Warner.

The goal, Mr. Negroponte says, is greatly increasing the donation program, “Give a Laptop. Get a Laptop. Change the World.” For $399, a person can donate an XO laptop and also receive one. Or donors can simply donate $199, to give a child a laptop, at www.amazon.com/xo.

The advertising time is donated, and the spots are expected to start conversations. One spot is an uplifting vision of a 7-year-old girl in a South African township, sitting in a dark room, her face lighted only by the laptop’s glow. “With education, we will solve our own problems,” she says.

Another TV spot says children learn quickly, whatever their tools of survival are — whether loading an AK-47 or mastering an XO laptop. Other settings show child labor camps and child prostitutes. “There are some very challenging scenes,” said Paul Lavoie, chairman of Taxi, the agency that created the ads.

Other innovative ads are in the works. Mr. Negroponte is talking to Yoko Ono about using lifelike digital images of John Lennon in ads discussing the opportunity to end the digital divide between rich and poor nations.

Marketing, Mr. Lavoie says, can help One Laptop Per Child move toward its original goal of a $100 laptop, which is possible only with the economies of high-volume manufacturing. “To get there, they need to sell a lot of computers,” he said.

By now, Mr. Negroponte insists, enough of these learning machines are in the hands of children in the developing world to see results. The children, from 6 to 12 years old, are more passionate about learning and educators are reporting fewer problems with discipline and truancy. “It’s unequivocally working,” said Mr. Negroponte, the founding director of the M.I.T. Media Lab. “The issue is the economics.”