It was a typical outing for the not-so-typical Flynn family. The 12 children had just piled out of the family's van looking like a mini-United Nations -- two black, two Oriental, two American Indian, one mixed heritage and five white.

"The manager of the McDonald's came over and asked me what we call ourselves," recalls mother Laurie Flynn. "I said "The Flynn Family.' She asked if we were entertainers and I said 'I guess you could say we're entertaining.'"

The Flynns are accustomed to stares and questions about their large, colorful brood. "Seven are adopted and five are homemade," they tell the curious.

Although these children represent a rainbow of races, there is a striking resemblance around the mouth: The Flynns are a family of smiles.

Their evolution began 20 years ago, when Laurie Flynn was a 14-year-old Arlington Girl Scout taking a trip to Junior Village, formerly a District facility for homeless children.

"I had never seen an institution before, and it made a deep impression on me," she recalls. "I was shocked to discover that the children had no parents and no other home. They were starved for love. They'd pull on me and call me 'Mommy.'

"I began to volunteer there, going to tell them stories and sing songs. I couldn't convince my mother, who already had five children, to adopt any of them. But she said I could adopt some when I grew up, never dreaming I'd really do it."

Joseph Flynn was the first serious boyfriend Laurie had who didn't run away when she said she wanted a large family.

("we hadn't really planned on 10," admits Laurie, whose eldest two are now grown, making her a grandmother at 34. "I wanted six and he wanted four, so we got 10.")

In the late '60s they began by having two children of their own. When Joseph graduated from Georgetown Law School they started making rounds of agencies, trying to adopt "special-needs" children: minority, older, physically or mentally handicapped hard-to-place youngsters. "The kind of kid," sayd Laurie, "I knew didn't go home."

"We were met with incredible skepticism," she says. "We weren't infertile so they couldn't understand why we wanted to adopt, especially across racial lines. They asked us what we were trying to prove and made excuses why we couldn't adopt."

But when they moved to Pennsylvania in 1970, so Joseph could take a legal services job, they had an entirely different reception.

"The agency was thrilled to see us," Laurie recalls. "Within three months we had Lea, 6-week-old infant of mixed racial heritage who was considered hard to place in that small community."

The family grew gradually over the mext 10 years. They had two more biological children before adopting a 6-month-old black child whose parents were both in institutions and considered "mentally limited."

"We didn't want Lea to grow up as the only black child in a white family," says Laurie. "That made the magic six and we had planned to stop. But in one year we gained four more."

They heard about a 14-year-old American Indian girl in Canada who needed a home, corresponded with her and found that she ahd a brother she hadn't seen for several years. They adopted both.

Then came another biological child and a 6-year-old Vietnamese boy. Two years ago they adopted a 3-year-old black child, and soon after a 15-year-old Vietnamese girl.

"We never hesitated when we heard about a child who needed us," says Joseph. "We consider it a privilege. I guess we're suckers for kids."

"It's an addiction," says Laurie. "If you take in a child who is supposed to be limited and you help make him or her successful, it's a very big high.

"People are always calling us saints, saying, 'Why would you want to adopt all those problem kids?' They just look at all the expense, worry and trouble, not at the fun, joy, hilarity and opportunities for learning about ourselves.

"We always felt one more child isn't that much more trouble. The first adoption is the scary one. The others are all easy."

Last fall the Flynns moved to Annandale so Laurie could take a fulltime job as director of the North American Council on Adoptable Children, where she had formerly been a volunteer.

"The family we rent our home from moved out because they though it was too small for their family of five," she says, smiling. "But it's perfect for us."

The entire family pitches in to run the home, with each child performing specific chores. Each week an older child is designated "top banana" and a younger one "second banana." The "bananas" arise a half hour early to set the table, put out the cereal and make the toast.

Grandmother Evelyn Flynn, who graduated from college at 62 and at age 65 is taking graduate courses, stays with the children each afternoon after school. Every weekend Joseph takes several children to the grocery store where they fill two or three carts with an average of $150 worth of food.

"People come to our door with toys, bikes, extra fruit and vegetables," says Laurie. (They've never received a penny for adopting children.) "At first we were embarrassed to accept, but then realized it's the community's way of saying, 'We like what you're doing and want to help.'

"We're not big consumers. We don't have a second car or second TV or spend two weeks at the shore. But I don't think we lead a Spartan existence. We've got enough.

"We don't spend a lot of money on entertainment -- we've got plenty right here. We have a whole baseball team, the cast of a Christmas pageant and enought entries for family art shows."

Sometimes they do get things "cheaper by the dozen." Their pediatrician charged them a group rate and the Catholic school where most of the children go charges the same tuition for nine as for three.

"But the big problem isn't how to feed or clothe them, but what to do with the odd socks," says Laurie with a laugh. "At last count we had 67 socks in the odd-sock basket. One of the little ones had the solution. She said, 'Why don't we adopt a child with one leg?'"

Although the Flynns "expected to be outcasts" in the community, they find "most people seem to support what we do. And the ones who feel negatively keep it to themselves.

"I know that outside the home the children get a lot of questions. But we try to give them a strong sence of identity and the ability to handle it. Sometimes one will come home crying because someone called them a bad name. We explain that even though we know it's what's inside a person that's important, some people just don't understand that.

"It's not that we're the world's perfect family. We've had problems, particularly with the teen-agers who already had a history of trouble in Canada. They didn't trust adults, were expelled from school and ran away from home.

"But we try to work things out in family council meetings. Since quality time is hard to find with so many, we give each child a chance to fill us in on what's going on in their life."

Antagonism between the biological and the adopted children is nonexistent, she claims. "But sometimes one will want to know why we can't afford go-karts or toys other kids have. I explain that we have different priorities in this family. We've chosen people over things."