Sophia, a teen-ager, chased LaToya, a 14-month-old toddler, around the sun-filled room at St. Ann's Infant and Maternity Home: mother and daughter at play.

For three months, the Hyattsville facility has been their home. They had nowhere else to go.

St. Ann's is also home to the four small brothers who wolfed down fish sticks and played with their mashed potatoes in a children's dining room elsewhere in the building. Social workers brought them to St. Ann's when their mother became sick once again, crying and screaming that she wanted to die.

And St. Ann's is home, too, to the pretty girl with the shiny brown hair and the maternity sweat suit, the newborn baby waiting to go home with his young mother and the little girl whose eardrum was punctured by a raging father.

For the last 125 years, St. Ann's and the Daughters of Charity have taken in thousands of troubled young women and children from the Washington area. The home, not widely known outside government agencies and welfare organizations, has been celebrating its anniversary for the past month with open houses and other special services.

Today, St. Ann's is both a discreet fragment of the past -- the area's only remaining home for unwed mothers -- and an up-to-the-minute social welfare agency. It has quietly evolved into a day-care center for community children, an educational program for young mothers like Sophia and a temporary foster home for the abused and neglected.

"Historically, St. Ann's has adapted its programs to meet the changing needs of society, of children and young adults," said Sister Catherine Norton, president of Providence Hospital, which handles deliveries and other medical needs for St. Ann's residents.

"St. Ann's is definitely one of our unique agencies," said Meredith Johnson, an official of the United Way of the National Capital Area. The agency provides 17 percent, or $297,000, of St. Ann's operating budget; the remainder comes from a small federal grant, several legacies and other private sources. It receives no church money.

"We have always had all faiths and races," said Sister Betty Ann McNeil, St. Ann's assistant administrator and a social worker. "We are not church-supported and we are not about the business of proselytizing. Our basic philosophy was, and is, we were here to serve the needy."

St. Ann's, its 110 employes and its several hundred charges occupy a rectangular brick structure tucked into a wooded area off Eastern Avenue just across the District line in Hyattsville. The furnishings are mismatched vinyl couches and tall bulbous lamps, but the floors are well-scrubbed and spotless.

St. Ann's began in 1860 in a building on the corner of 13th Street and Pennsylvania Avenue NW, across from the Willard Hotel. Troops then were quartered in the city and the number of orphans and illegitimate babies was on the rise. The nuns at St. Ann's Infant Asylum, as the facility was called, took them in. During the next 60 years, homes were found for 8,000 babies.

St. Ann's ceased to be an adoption agency in the 1920s when Catholic Charities took over that function. It has been located at several sites in the city, but in 1962 the home moved to Hyattsville.

With the 1960s came the big changes within St. Ann's.

"More mothers were working. More families were breaking up. The foster system was jammed with kids," Sister Betty Ann said.

Not only that, but the stigma that once drew unwed mothers to facilities such as St. Ann's began to lessen. The leaders of St. Ann's looked around at what was happening in the community and gradually began to add day care, foster care and other programs.

"We had always had unwed mothers, and we knew we would continue to help them," said Sister Betty Ann. "But we also felt that we should adapt to meet the changing needs of society -- the children who were abused or neglected, the working parents who needed day care. Our main goal was service and those were the things that needed to be served."

On any single day, 130 babies and preschool children are part of the day-care/early education program at St. Ann's. Their parents pay for the service on a sliding scale, based on income.

As many as 55 other children live at St. Ann's until their home situation is straightened out or they can be placed with foster families.

"These are emergencies, kids in danger," said Sister Betty Ann. "The children we deal with are so terrorized, they've been so traumatized, they don't have the yearning we call homesickness. But many's the kid who has slept that first night with his clothes on. They don't like to expose themselves."

The third major group at St. Ann's are the pregnant women, who come for the privacy, and the young mothers who need help in learning how to care for their babies and straighten out their personal lives.

Usually, about 25 women are involved in St. Ann's maternity services. They continue their schooling in accredited classes held in the building. They also get emotional counseling and career advice from St. Ann's staff of psychologists.

"We try to involve the fathers in counseling," said Sister Betty Ann, "but they are an elusive group. Most guys don't stick with the girls."

Nor, in some cases, do the girls' parents. Sophia's is a case in point.

When Sophia was 14 she became pregnant, and discovered that her father would not forgive her.

She is 16 now, a tall, slim young woman whose face becomes animated when she speaks. For the first time in several years, Sophia believes things may turn out all right for her and LaToya, a chubby little girl with braids.

"LaToya and me, we're by ourselves," Sophia said. " . . . . I've had to learn a lot of things on my own. St. Ann's has helped me to be a lot more independent. I go to school here and that's good.

"I always had this dream that I wanted to go into the Air Force someday. With LaToya, I don't know . . . . But I tell you, I look at her and I'm glad I had her. I'm proud to have her. I'm a very proud mother.We'll be okay."