BUDAPEST -- Frank Clark arrived here from Manchester, England, two years ago with his wife, 2-year-old son Sebastian and a desperate cause: finding help for a child so handicapped by cerebral palsy that he was unable to stand or even sit up on his own.

Hungary, a communist-ruled country of modest economic means, seemed an alien and unlikely haven for a middle-class British family seeking specialized therapy. But Sebastian had been unable to get the intensive care he needed at Manchester's public health clinics, and Clark had heard that an institute here had developed a uniquely successful treatment for cerebral palsy, Parkinson's disease and other motor disabilities under the name of "conductive education."

"We felt," said Clark, "that we had no choice but to try." And now, after two long and often painful years, the Clarks feel that their gamble -- and sacrifice -- has paid off. Entering his third year of intensive treatment at the Peto Institute, Sebastian can go to the toilet, button his shirt buttons, eat and stand on his own. He speaks fluent Hungarian as well as English.

At last, with a hand of support from father or mother, Sebastian can walk -- a landmark achievement for most cerebral palsy-afflicted children. "He does things we couldn't have dreamed of," says Clark. "And I'm convinced he never would have done it if we had stayed at home."

Sebastian's story is part of a testimony of hope that is propelling the Peto Institute and its "conductive education" toward international fame -- and the onslaught of opportunities and risks that come with it.

In the two years since the Clarks arrived here, the facility has gone from the status of a specialists' rumor to an almost mythical renown in Britain, and curious experts and parents have begun to arrive from as far away as Israel, New Zealand, the United States and Japan.

Peto now has 100 foreign children, including about 60 from Britain, among its 1,700 patients, and more than 1,000 foreign families have applied for help.

It remains unclear whether the Peto Institute's remarkable reported success with motor disabilities can be duplicated elsewhere. But after 32 years of dogged persistence, the institute appears to be on the verge of vindication in its insistence that traditional therapy has long failed to realize the potential for helping the severely handicapped.

"We have done always the same thing with always the same results, and so it is interesting that it is being noticed only today," said Dr. Maria Hari, who joined founder Andras Peto at the institute's beginning and is now its director. "Anyway we are glad to be known, even if we can't develop as quickly as the demand -- because it's good for the children."

Hari, a slight, gray-haired woman of intense dedication and drive, inherited the de facto stewardship of conductive education in 1967, when her mentor Peto died. By her account, he was a brilliant, enigmatic doctor who spent his formative professional years in Vienna between the two world wars. In 1946, Hungarian authorities grudgingly allowed him two rooms and 13 handicapped children deemed hopeless to try out his radical ideas.

"Within a year, 12 of the 13 were walking, an accomplishment the doctors found unbelievable," Hari said. "So Prof. Peto was allowed to carry on with his practice, though we had to go through many fights before it was fully accepted."

At the heart of Peto's conductive education theory is the notion that what motor-handicapped persons need is not targeted therapies but a global, integrated treatment. "Traditionally people think handicapped children are ill and need therapy," said Hari. "That's not true: they have an incurable illness and the key is for them to learn how to live with it."

The Hungarian method abolishes the traditional division of treatment, and specialists, into speech therapy, motor therapy and psychological therapy in favor of a unified approach and a single therapist -- the "conductor" -- who guides the child through complex activities meant to address several problems at once.

The mechanical implications of this can be seen easily in one of the institute's simple, neat classrooms, where children simultaneously stand and work on a puzzle, grasp sticks while sounding syllables, or walk while acting out a simple story.

In psychological terms, Clark said, the technique means "a total commitment to the child 24 hours a day. Even when they play in the afternoon they are incorporating the exercises they learned in the morning. And if a child takes an hour to walk to the door, the conductor will take that hour -- they never give up on the child."

Conductive education uses little technology other than a few simple tables and chairs and is geared toward integrating children as quickly as possible into a society where there are few, if any, special aids for the handicapped.

According to Clark, the people at the institute "insist that the child must learn to do everything, that he must be self-reliant. It was a terrible shock to Sebastian -- and to us -- when we first came here. but then he started to do things for himself we never imagined he could do."

The Peto Institute has said that 70 percent of the handicapped children it treats eventually learn to walk, a remarkably high success rate. It often takes a severely disabled child as long as five years to reach that goal, but once it is achieved it is usually a permanant gain. Hari said that 90 percent of children affected by cerebral palsy can be helped by the technique.

For both the director and the growing cast of foreign admirers, the critical problem is how to transfer the institute's success to places outside Budapest. Therapists in Britain and occasionally other foreign countries have attempted to adapt conductive education, but none have had Peto's results.

Hari, whose personal talent is sometimes singled out as the real source of the institute's quality, insists that conductive education has been badly applied in other countries. "It's a complex learning process that can't be done quickly," she said. "It takes four years to qualify a Hungarian conductor and the best, the ones who lead, have been doing it 20 years. But we have people who come here for six weeks and take notes and then go back and try to do it. Of course they fail."

The troubles of spreading the technique have brought the Peto facility to the brink of crisis. Even as the average waiting period for foreigners seeking an interview has stretched to one year, Budapest has been visited by recruiters from private clinics in Britain and the United States hoping to hire away the most experienced conductors.

Hari has reacted by threatening to expel foreign children from the institute and cancel her agreements to train foreign conductors.

The only solution, all parties agree, is a more rapid dissemination of the Hungarian experience. "I know that this is a system that can be transferred," Hari said. "What is necessary is commitment -- commitment to the education and commitment to make it work."