They fell in love 20 years ago. In an auditorium decorated with crepe paper. At a Virginia mental institution.

"He asked me to dance," remembers 37-year-old Lilly Mae Wise, who spent more than half her life inside the Lynchburg Training School and Hospital.

"She was standing by a pillar," says David Wise, who was sent by his mother to the Lynchburg school when he was 14 because he, like Lilly, is mentally retarded.

David and Lilly don't talk much about Lynchburg these days. They are too busy working full-time jobs, paying bills, and dealing with the general complications of marriage and suburban living.

"They are not your usual love story," allows Maureen McGuire, a Fairfax County rehabilitation counselor, who nominated David and Lilly for Virginia's "Rehabilitant of the Year," an award the couple will receive this weekend from the Virginia Rehabilitation Association.

"We deserve it," said David Wise, with an innocent candor that characterizes his approach to a life that differs surprisingly little from those of his neighbors in Fairfax's Centreville neighborhood.

David and Lilly's success would not have been possible even 10 years ago, say community service officials, who point to the Wises as an example of how the decade-old movement to mainstream this country's 6.5 million mentally retarded people is supposed to work.

"There has been a lot of progress in the move away from keeping the retarded in large institutions," says Myrl Weinberg, an official with the 300,000-member National Association for Retarded Citizens, one of the oldest organizations in the field. "The number of community-based group homes and community programs for the retarded has grown considerably," Weinberg says.

In Northern Virginia, for example, there are a dozen public and private service organizations that deal primarily with mainstreaming -- the effort to help mentally retarded adults make the transition from life inside an institution to a productive place in the community.

David and Lilly Wise benefited directly and indirectly from four such programs. But their counselor says the couple deserves more credit than any combination of the well-intentioned programs.

"It's really a neat story because they did so much of it on their own," says McGuire, who didn't get involved with the couple until David Wise had obtained Lilly's release from Lynchburg.

"We don't know exactly how he did it," laughs the 27-year-old McGuire. "But he managed to finagle the social services people, the training center, and anybody else he had to, in order to get Lilly released in his care.

"He's not book smart, but David really knows how to manipulate a whole complex system," she said.

David Wise, now 37, was in the first wave of mentally retarded patients given a chance to try life on the "outside" with some supervision. In the eight years since he "graduated" as officials put it, from Lynchburg, Wise has worked as a helper on a Pepsi truck, a short-order cook at two fastfood restaurants, and a dishwasher at a few more.

During that period, he lived with his mother in her Centreville apartment and never gave up trying to get Lilly out of Lynchburg.

Every three months, Wise would make a 163-mile bus ride to see Lilly. Every month he sent her a package of clothes and money. Aware that she would need to show evidence of being able to work in the community, David encouraged her to study housekeeping.

Four years ago, Lilly was transferred from Lynchburg to a state-run training center in Northern Virginia. Within a few months she was participating in a program called "Project Transition," learning to be a dishwasher.

"I'm the best dishwasher in Virginia," brags Lilly, who now works in a Centreville restaurant just a few blocks from the two-bedroom apartment she and her husband share with his mother, Lillian.

David does most of the cooking and the two women share housekeeping duties. "David makes the best wholewheat bread and light rolls you ever had," brags his mother, while David searches through a recipe box for his original culinary creation -- Jewish apple rum cake.

"Wherever he makes that," says 66-year-old Mrs. Wise, "there's never a slice comes back."

David's boss at Baxters Esquire Restaurant in Fairfax City, executive chef Thomas Fernandes, says he initially was apprehensive about hiring Wise to wash dishes. But now Fernandes describes Wise as a "versatile employe" and a "true friend."

Life for David and Lilly Wise is not without its humiliations and frustrations. Occasionally one will get on a wrong bus. Frequently both will encounter stares and worse from allegedly more intelligent people.

"Remember that cook," said David to Lilly, as they sat together in their apartment, tracing their lives. "He hurt my feelings," said Lilly, turning her face as her eyes began to water.

Lilly was one of 4,000 patients at Lynchburg who was sterilized without consent during the period from 1924 to 1972. But neither she nor David are bitter about that.

"We couldn't take care of children anyway," David said. "It's hard just taking care of ourselves."

Routine living for David and Lilly Wise includes church on Sunday and regular treks along Rte. 50 in search of abandoned treasure.

During the last five years, David and Lilly have returned enough soft drink bottles for deposit to build a bank account to $1,000.

Ironically, their success has cost them the monthly social security payments they were receiving as disabled persons. As a result, they are now totally independent of any public aid.

"They're very proud they don't get welfare or food stamps," says McGuire."They're very proud of everything they have. They're really making it."