At first they were stunned when their adult son, the ninth of 10 children, was diagnosed as suffering from paranoid schizophrenia. Then they were confused when they learned that the best advice from professionals, to get him into a specialized group home, was a fantasy.

"We went marching out saying, 'Where do we sign up {for a group home}?' " Bill Snavely said. "There weren't any."

That eventually sent Snavely, an Alexandria resident, marching in a different direction -- to Richmond. There, he is the chief spokesman for an unusual coalition of interest groups trying to cajole, wheedle and generally pressure the General Assembly into approving the largest initiative ever in Virginia for mental health, mental retardation and substance abuse programs.

Once organized, members of the Coalition for Mentally Disabled Citizens of Virginia helped put together a detailed proposal, wrote to and met with Gov. Gerald L. Baliles to push it, contacted all of their legislators, came out for hearings around the state -- creating enough noise that they had to be heard.

They succeeded in getting a substantial financing increase in the governor's proposed budget and are working on getting more from the legislature.

"They have done an amazing grass-roots organizing job," said Sen. Joseph V. Gartlan Jr. (D-Fairfax), a longtime supporter of increased funding for the mentally disabled.

Many of those lobbying the legislature are, like Snavely, middle-income parents or other relatives of mentally disabled people who have pulled together their fervent but disjointed efforts.

Others are professionals in the field and advocates who previously had been dogging each other's footsteps, competing for funding.

"We were arguing about dividing up a nonexistent pie," Snavely said about the competition among the groups before the coalition was formed 15 months ago.

"We were being placated by token contributions."

Snavely, a retired military veteran who was working at a defense research and consulting firm, got involved with a family support group shortly after his son was diagnosed seven years ago.

He then decided to take a year off work to do intense volunteer work.

"I never went back," he said.

Snavely now is president of the National Alliance for the Mentally Ill, with headquarters on Fort Myer Drive in Arlington.

Created in 1979, the alliance has affiliates in each state and thousands of families as members. He is a past president of the Northern Virginia Alliance for the Mentally Ill, and has served as a member of the Alexandria Community Services Board, which directs local services to the mentally disabled.

The Coalition for Mentally Disabled Citizens of Virginia was formed in late 1986, and Snavely chairs it, as well. The position, like the others, is a volunteer job.

The 10 groups that joined forces under the coalition are the Virginia Alliance for the Mentally Ill, the Association for Retarded Citizens of Virginia, the Virginia Association of Drug and Alcohol Programs, the Mental Health Association of Virginia, the Mental Health Association of Northern Virginia, Psychiatric Society of Virginia, Parents and Associates of Institutionalized Retarded, International Association of Psychosocial Rehabilitation Services, Commonwealth Clubhouse Association and Henrico Citizens for the Mentally Handicapped.

Christopher J. Spanos, a veteran lobbyist for the American Civil Liberties Union in Richmond, also represents ARC, a member of the coalition. He has helped the coalition pull together its efforts, guiding its energies to the right places.

"The coalition members had to take their frustration and anger and channel it into a program," Spanos said. "The problem with some advocates is they walk in and say, 'Do something.' "

The groups do not agree on all issues. The mental health association, for example, supports strong protections against inappropriate commitment of mentally ill people. Members of the alliance, primarily parents of schizophrenic children, generally believe that the laws have gone too far in making it difficult to obtain commitment of mentally ill people who need help but are not openly dangerous.

The groups found common ground to work from, however, in the need for special housing programs and day support, and that became the focus of the coalition's request for a funding initiative.

The 40 community services boards around the state were told to document their needs. The Virginia Department of Mental Health, Mental Retardation and Substance Abuse compiled the information from around the state and used it to develop a $140 million community services initiative proposed to Baliles for inclusion in his fiscal 1988-90 budget.

Baliles' budget request, announced earlier this month, contained $65 million for the initiative. While coalition members praised the governor for proposing the initiative, which would be the largest single increase ever for these services, they nonetheless were disappointed that the funding was not closer to the $140 million request.

The coalition is turning its attentions to the General Assembly, accelerating a campaign it started last year of writing and visiting key senators and delegates. Spanos said he and Snavely went to Norfolk three times before the legislature started to visit Del. George H. Heilig Jr. (D-Norfork), who as chairman of the House Appropriations subcommittee on human resources will play a key role in funding programs for the mentally disabled.

Members of the money committees are faced with requests for millions more in funding for other state programs and they must juggle all interests while keeping the budget balanced. Some key members, including state Sen. Dudley J. Emick Jr. (D-Fincastle), chairman of the Senate finance human resources subcommittee, have said that although a substantial funding increase is warranted, the $140 million figure is unrealistic.

It took some time for families of the mentally ill to come out in public. Mental illness still has a stigma, and families often thought their difficulties were unique and temporary. As they began to talk with each other, however, they started to get bolder. Some of the most stirring testimony at hearings last summer came from family members talking frankly about their difficulties in coping with mental illness.

The genesis of the coalition was a conference in Williamsburg in 1985 chaired by Emilie F. Miller, now a Democratic state senator from Fairfax, and attended by members of all the advocacy groups, according to Spanos and Miller.

The state had done studies documenting needs of the mentally disabled before, but little came of them. Another completed in 1986 noted the continuing gaps in services and said that not much had changed since a 1979 report outlined the large, unmet need for special housing in the decades after deinstitutionalization of the mentally ill.

"These issues are apple pie and motherhood, but the legislature has to know there is grass-roots support for this money," Miller said. To do that, the advocates had to speak "as one voice."

Whether the coalition can succeed in getting substantially more than what is contained in the governor's budget will become clear within the next few weeks as the budget wends its way through the money committees of both houses. Members of the 10 groups, often seen wearing buttons or sweatshirts with the coalition's "Make Waves Virginia" slogan, will be coming to Richmond from around the state to keep tabs and to make their delegates conscious of their continuing interest.

"This effort is not going away. It is a six-year plan," Miller said. "They {the coalition's members} are going to be there. They are organized. They have seen what they can do."