Valerie Karr is the author of UNICEF's "It's About Ability: Activities for Learning and Taking Action on the Convention on the Rights of Persons with Disabilities."

Alaskan Gov. Sarah Palin steps down from office on Sunday. And while the media remain obsessed with her travails, she leaves with at least one definitive achievement since she burst on the national scene last year: She provided a much-needed showcase for children with special needs.

Never before in American politics had the cause of children with disabilities received such prominence and star wattage. The loss of such a powerful advocate in public office will be felt across the disability community. The vulnerable, wherever they are, always need heroes.

According to the 2000 Census, more than 50 million people in the United States experience some form of disability, and 13.7 percent of school-aged children receive services for a disabling condition. When you add the extended networks of family, friends and caregivers, the number of people affected by childhood disability expands exponentially.

Advocacy, more so than policy, is the key to making people with disabilities full members of society. Sure, we have laws that prohibit discrimination and promote opportunity. But there is still an overwhelming insensitivity toward persons with disabilities.

And that's where Palin can continue to play a crucial role. One of the key challenges for children with disabilities is building society's acceptance of them. As a bona fide national celebrity who shares the pains and joys of millions of families who have a child with a disability, Palin can contribute uniquely to promoting the social change needed for her son, Trig, who has Down syndrome, and the millions of his peers.

While juggling the positions of mother-advocate and public official proved difficult, Palin has continued to speak out. In June, she was honored at a fundraiser for Long Island's Independent Group Home Living, and she participated in a fundraising walk for Autism Speaks.

Palin isn't the only high-profile disability advocate, of course. Today, President Barack Obama is expected to sign the United Nations Convention on the Rights of Persons with Disabilities, which passed the UN in 2006 without U.S. support.

The Convention represents an international consensus on the equal worth of children with disabilities - their acceptance and treatment varies widely around the world - and establishes a stringent national and international monitoring system.

Obama also appointed three people at the White House to handle disability issues and showed his support of liberalizing embryonic stem cell research by overturning federal funding restrictions. Many doctors and scientists believe that stem cell research could be a key to the discovery of causes, treatments and perhaps cures to certain childhood disabilities.

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But changing laws is easier than changing hearts. And even with these efforts, the fact that dangerous stereotypes exist in our society - take, for example, a gaffe not so long ago by Obama himself, when he compared his bowling skills to the Special Olympics - means that people with disabilities will continue to be underestimated and shortchanged.

That's where Obama can take a page from an unlikely source. Palin has put a human face on disability and demonstrated to the country the love and commitment that families and caregivers have for their special children.

For the first time, millions of Americans not personally affected by disability realized the inherently political issues affecting those with disabilities, including the need to provide access to schools, work, research, health care and community support.

Palin will be missed - and not just by talk-show hosts starved for a figure to poke fun at. Disability is a cause with far too few national champions. As she steps down from the governorship, let's hope she steps up even more as a staunch disability advocate.