Shirley Ceasar is 27 years old, and she's expecting her 10th child. But another baby won't be a burden for her. Like the rest of her kids, the child will be taken care of by its grandmother.

Shirley, a crack addict for at least four years, lives in Harlem with her boyfriend, the father of all her children. Her mother, Sarah Mae Ceasar, lives a 15-minute subway ride away, in a housing project in lower Manhattan.There, in a cramped three-bedroom apartment, Sarah Ceasar takes care of five of her grandchildren, including 11-year-old Walique, who was born deaf and mentally retarded. Shirley's other children are cared for by their paternal grandmother.

"I used to go up and see them and there was nothing in the refrigerator to eat, no clothes for them to wear, they weren't even going to school," said Sarah Ceasar, 57, who is hoping to adopt the children. "I'd bring them clothes. Their father would sell the clothes for drugs."

In New York City and other large metropolitan areas, grandmothers like Sarah Ceasar are the glue holding together many poor black families splintered by drugs.

In the past five years, the crack epidemic has made addicts of more young minority women than any other drug in history. In particular, experts say, it has threatened the tradition of black women who often hold their families together.

"There's a quality in crack that is so quickly addictive that people don't get away with experimenting with it," said Richard Johnson, director of the Jewish Child Care Association of New York. "Women who would normally retain some responsibility and some conscience about their children don't have the chance. They're addicted so quickly. They're just lost."

Since 1985, the number of children in New York City's kinship foster care program, which allows grandmothers and other relatives to receive aid for taking care of dependents, has jumped from 150 to 17,000.

Seventy percent of the placements of children within kinship foster care are the result of mothers' crack addiction, Johnson said.

"Certainly the absence of a father is bad, but now the mother is missing," said Melba Hamilton, director of the Harlem Dowling Children's Service. "These children are facing a very bleak future."

And as a result, grandmothers such as Sarah Ceasar have been called upon to assume enormous family burdens.

They are mostly Southern women, tied to a rural past while mired in the harsh economic realities of the inner city, according to social workers. Many came to New York as newlyweds, hoping for a better life. Most have outlived their husbands and lost some of their children to drugs and the streets.

Now they must become mothers again, sometimes caring for children born toxic and mentally handicapped because of their mothers' addictions.

"A lot of the grandmothers are really exhausted and would like to not have to do this," said Johnson. "But if it has to be done, they're going to do it."

Some grandmothers care for their grandchildren on an informal basis. But a growing number are taking advantage of kinship foster care and the financial aid it offers. Depending on the age of the child, foster grandmothers are allowed anywhere from $450 to $900 per month for their care.

Despite the strain the grandchildren add to their lives, some grandmothers are surprisingly resilient and learn to enjoy having kids around again.

Some are younger than the stereotypical grandmother. In the words of Lorraine Hale, director of Hale House, a Harlem home for the children of unwed, working and drug-addicted mothers, "They don't all wear their gray hair in a bun and act wise." But they're often realistic when it comes to the problems of their own children.

"It's not my fault," said Sarah Ceasar of the drug addiction of her daughter, Shirley, and her other children. "It's their fault and it's their life. If they don't want to make anything out of their life, there's nothing I can do about it."

Her grandchildren remain loyal to their parents but said they love their grandmother and the security of her home.

"She takes us out places and does a lot of things with us," said Rasheeda, 10. "I like being home with her instead of a foster home."

The children's father, Lorenzo Adderley, 28, also said he was grateful to Sarah Ceasar. As he stood in the doorway of the Harlem apartment he shares with Shirley Ceasar, whom he met when he was 14, Adderley said he was looking for work and that Shirley soon may go into a drug rehabilitation center.

Sarah Ceasar said both Adderley and her daughter are addicts. Adderley said Shirley was but denied that he was an addict, though he appeared to be under the influence of drugs during an interview. Shirley Ceasar declined to be interviewed.

Sarah Ceasar, who was born and raised in Sumter, S.C., is not unlike many of the grandmothers who look a decade or more older than their age, testament to unusually harsh lives.

Her life story, the details of which she recounted stoically in her living room as her grandchildren did their homework at the dining room table, has been one of frequent tragedy.

Her father was an alcoholic who beat his wife and children and forced her to begin work in the field picking peas and corn at the age of 8. Two of her brothers were murdered as young adults. She got pregnant at 13 and married the father.

After the family moved to New York, one of Sarah Ceasar's sons was strangled at age 17 and another died of a heart attack in her living room at age 30.

Seated in a Manhattan social services office with her caseworker, Blanche Giles, 68, who arrived in Harlem from Atlanta in 1949, recounts an equally tumultuous life.

She copes by rising at 5 a.m. every day and opening to the 91st Psalm in the Bible she brought from Georgia.

"It opens up the day for me," she said. "It keeps me going."

Viola Jenkins, 63, has lived in the same apartment building in the South Bronx ever since she arrived in New York from her native Fayetteville, N.C., in 1945. Her husband, with whom she had four children, died in 1982.

Since 1985, she's taken care of her grandson and granddaughter. They were placed in her care after authorities were tipped off that the children were being tied to the radiator in the apartment they shared with their parents, who fought often and were involved with drugs.

Every morning, after the kids leave the apartment for school, Jenkins walks over to her bedroom window. She keeps a pillow there to rest her elbows while she gazes out onto Union Avenue and watches her two grandchildren until they disappear from sight.

"I can see them almost all the way to school," she said on a recent morning as she craned her neck out the window. "If I try to walk them to school, they think I'm treating them like babies."