When the Virginia General Assembly passed its $60 billion budget in May, it included an unprecedented amount of money for the mentally disabled. With nearly $40 million set aside, hundreds of people with cerebral palsy and other conditions who had languished on waiting lists were promised placements in group homes or visits from home health aides.

But many now authorized to receive services are finding that providers are in short supply, and they must continue to wait for assistance they thought they were guaranteed. Others are getting only a portion of the services they say they need.

All across Northern Virginia, agencies that deal with the mentally disabled are experiencing difficulties hiring and retaining staff to care for clients.

The problem is tied to the national shortage of health care workers, including home health aides, nurses and other providers, state and local authorities said.

In addition, Virginia's Medicaid program pays agencies a small amount of the actual cost of providing services. That has meant agencies are unable to provide the comprehensive services many of their clients have been waiting for, state and local officials said.

Although the entire state is affected by these staff and funding shortages, the problem is especially acute in the Washington suburbs because the cost of living is 20 percent higher than in rural areas, according to state statistics. That makes Northern Virginia a relatively less attractive place for providers to do business.

"In many cases we just don't have the places to send those who need the help," said Odile Saddi, director of disability services for Arlington County, who is responsible for linking mentally disabled people with providers of care.

For advocates of the mentally disabled, the shortage of providers is a sobering reality in light of the fight they waged in the state legislature this year to extend care to 860 more people.

The resulting legislation entitled certain people with mental disabilities to live in group homes or receive visits at home from health aides, and to purchase specialized equipment with a combination of state and federal financing. The services, based on eligibility requirements, are granted in lieu of placing those with mental disabilities in large institutions.

Not enough money was approved, however, to enable Northern Virginia localities to serve eligible people, advocates and state officials said.

"We were so focused on getting more slots that I don't think we fully appreciated the problem of costs last year," said Nancy Mercer, executive director of the Arc of Northern Virginia, an organization that works on behalf of the mentally disabled. In some cases, Mercer said, agencies have been forced to increase the number of residents in group homes because it is more cost-effective.

Part of the problem is that services for the mentally disabled are provided largely by private agencies. Many of these are nonprofit organizations that are reluctant to take on more clients because the state's payments are not high enough to cover their costs.

"We are being stretched just way too thin," said Silva Bey, executive director of Community Living Alternatives, an agency in Falls Church that has 19 facilities across the region.

Bey said the state pays her agency about $13 an hour to help those with mental disabilities. But employing one worker to do that job costs her $26 an hour -- for training, salary, insurance and other expenses. That kind of money-loser, she said, makes it difficult for a facility to provide complete services to those who are entitled to them.

The economics of such services also discourages agencies from setting up in Northern Virginia -- which, in turn, limits the choices for those seeking providers.

For example, Marge and Joe Rickerson, a couple in Fairfax County, waited two years to receive a waiver that would pay for day services for their daughter, Ellen, a 24-year-old who has cerebral palsy. After finally being told in April that they would be getting the necessary services, they were forced to wait for several more months, for lack of someone to provide the service. That led them to take a drastic step: "We took out an ad in a few local papers," said Marge Rickerson.

She said she understood that many agencies are in a tough position.

And although the Rickersons ended up receiving some of the services without having to foot the bill, they are still waiting for others, including a lift needed for their van to transport Ellen.

State officials who are responsible for providing services to the mentally disabled said they are trying to understand the extent of the problem. In many cases, they said, families entitled to services will get at least some of them, but in many cases they might not get all of what they are entitled to.

"What we're hearing from many providers is that many of them are losing money," said Clarence "Lee" Price, director of the state's Mental Retardation Services. The results of the state's analysis will be available next week, he said.

Some lawmakers anticipated the funding shortage and tried to address it during the General Assembly session. Sen. Charles J. Colgan (D-Prince William) submitted legislation, without success, that would have given $25 million to localities in Northern Virginia to help defray the higher costs of doing business in the region. Such funding is available for other care providers, such as nursing homes, state officials said.

"We got a lot for mental health services" in the last session, "but there just wasn't the money to do it all," Colgan said. With a budget surplus projected for this fiscal year, he said, he hopes the state can fund the difference in costs for Northern Virginia.

"I think we'll be able to push something though," Colgan said.