With row upon row of disabled Americans cheering and sometimes weeping with happiness, President Bush yesterday signed landmark legislation banning discrimination against the disabled, declaring, "Let the shameful wall of exclusion finally come tumbling down."

The legislation, considered the world's strongest civil rights protection for the disabled, prohibits discrimination in employment, public accommodations, transportation and telecommunications. Bush backed it strongly, and Congress approved it despite opposition from some business groups who argued that it would be too costly and would produce an explosion of lawsuits.

The president appealed directly to business. "You have in your hands the key to the success of this act," he said, "for you can unlock a splendid resource of untapped human potential."

Some 2,000 disabled visitors and their families, some in wheelchairs, some deaf with interpreters, some blind with seeing-eye dogs, attended the ceremony to create what Bush called "this splendid scene of hope spread across the South Lawn of the White House."

He likened the day to America's Independence Day celebration, saying that with the new law, "Every man, woman and child with a disability can now pass through once-closed doors into a bright new era of equality, independence and freedom."

Today, Bush said, "America welcomes into the mainstream of life all of our fellow citizens with disabilities. We embrace you for your abilities and for your disabilities, for our similarities and indeed for our differences."

The president said a major goal of the legislation is to demonstrate that disabled Americans want to work to support themselves and maintain independence. Many cannot do so because employers will not hire them; many businesses and industries are not equipped to accommodate wheelchairs and other special needs of the handicapped; and buses, trains or even taxis equipped for the disabled are not routinely available. Much of that will have to be corrected in phases under the Americans with Disabilities Act.

Bush said taxpayers now spend almost $200 billion a year to support Americans with disabilities -- "in effect, to keep them dependent. When given the oportunity to be independent, they will move proudly into the economic mainstream of American life, and that's what this legislation is all about."

The massive ceremony, one of the largest on the White House grounds since Bush took office, was held without any apparent hitch.

Administration officials originally had wanted a much smaller signing ceremony inside the White House for fear the Washington summer heat would cause the disabled too many medical problems. But representatives of the groups involved insisted on a major outdoor ceremony, and that was what they got.

The law defines a disability as any physical or mental impairment, including AIDS, that substantially limits a "major life activity."

Sandra Swift Parrino, who heads the National Council on Disability, said the legislation "heralds a new beginning for the 43 million Americans with disabilities and their families." She said it is "critically important, because its provisions will shape the lives of those with disabilities for decades to come."