WASHINGTON -- Eunice Kennedy Shriver was a civil rights hero, and unique even in that select company. Most civil rights revolutions are made by rhetoric and law -- ignited by protest, summarized in memorable speeches and confirmed at bill signings. In founding the Special Olympics, Shriver led a revolution of sport and competition that forever changed the way Americans view people with intellectual disabilities, and the way that many of the intellectually disabled view themselves. It was America's most joyful civil rights movement -- a revolution of play.

Half a century ago, as she began her activism, images of the mentally retarded (as they were then called) were anything but joyful. They were among the most isolated, overlooked and oppressed citizens in America, often hidden in remote institutions, restrained and medicated, unacknowledged by their families. Placed into clinical categories such as "idiot," "moron," and "imbecile" -- the official, scientific designations -- the intellectually disabled were sometimes subjected to involuntary sterilization and prevented from marrying.

When Shriver began a sports camp for the mentally disabled in her Maryland backyard in 1962, she had little idea what activities they were capable of performing -- because few had ever bothered to physically challenge them. Her own mentally disabled sister Rosemary, however, had been a fine swimmer. So Shriver pushed the children to ride horses, climb trees, jump on a trampoline, and play kickball and tennis. The Special Olympics grew out of this camp, introducing Americans to gymnasts with Down syndrome and runners with intellectual disabilities, striving to the tape. Medals are awarded, parents are proud, crowds cheer -- and images are produced that defy generations of prejudice and fear.

It is, in some ways, an odd movement, applying the values of the Kennedy clan (relentless competition, high expectations, rough play) to a community from which people expected little. Tim Shriver, chairman and CEO of the Special Olympics, describes his mother as "very tough, very demanding." "I never saw her baby an athlete," he told me the day before her death on Tuesday. "She never applauded a last place finish. She wanted to see achievement -- for athletes to run strong, to swim strong. She never had a low expectation problem -- what the mind couldn't do, she thought the body could. It wasn't 'everybody is a winner' -- that wasn't her."

When some objected that defeat and disappointment might be hurtful to the intellectually disabled, Eunice Shriver dismissed the idea as "baloney." Most people, she responded, cry when they lose. Her compassion cannot be called sentimental. But it was more compelling for its lack of sentimentalism. The rigor of her expectations was an affirmation of the dignity and possibility she saw in the intellectually disabled. She did not find disability incompatible with excellence. These are the kinds of high expectations that have helped many of the intellectually disabled into public schools, apartments, jobs and a measure of independence.

Shriver, by all accounts, was among the most talented and driven of the Kennedy siblings -- restless, sharp, impatient, the quarterback at family football games. But the avenues for her ambition were limited by her times. "Politics was not an option," Tim Shriver recalls, "but she still wanted to push for change. So she decided to change society from the bottom up. She was a social entrepreneur before anyone heard of the term."

Precisely because Eunice Shriver, along with her remarkable husband Sargent (the first director of the Peace Corps), often acted outside the partisan realm -- calling Americans to their better selves of citizenship and service -- the couple transcended political divisions better than their contemporaries. Ronald Reagan awarded Eunice Shriver the Presidential Medal of Freedom. Generations of public officials, Republican and Democrat, supported and admired her work, which now reaches to 120 nations.

Shriver seemed to have many motivations for this work: her highly developed sense of justice, her Catholic faith, her love for Rosemary. But all these influences led in the same direction. She refused to accept that anyone was hopeless or worthless. She believed that great causes could involve great joy. And she practiced a kind of vigorous love that did not stroke or pity, but rather transformed.

Compared to her brothers, Eunice Shriver's options may have been limited -- but her achievements were not inferior. It is difficult to imagine a higher purpose, or a finer epitaph: She made her nation a more welcoming place.