Social worker Barbara Cotton treads lightly when she goes to the one-story, middle-class house in Prince William County. Too little guidance, and the two children in this house could suffer again from parental neglect. Too much, and the mother will tune her out and stop cooperating.

Cotton started working with the family about a year ago after a report that the young parents, binging on booze and drugs, would lock their infant and 5-year-old in a bedroom all night and well into the next day. They originally denied it, but the 5-year-old told the social worker it was true, and there was the telltale lock on the bedroom door.

Now the young woman has moved in with her mother and says she understands she must clean up her life and give her children the attention they need. But she has little money, no place to move and she is pregnant again.

Cotton and other suburban social workers have been flooded recently with cases like that one, as well as others more severe. Prince William County had 452 cases of substantiated or probable child abuse and neglect in fiscal 1989, up 66 percent from three years earlier. Child deaths from abuse have more than doubled in Virginia since 1986, from 14 to 34. Five of the deaths in fiscal 1989 were in Northern Virginia.

Much of the increase in child neglect and abuse has been attributed to higher drug abuse among young parents, which suburban social workers say affects between a quarter and half of their cases. Other factors they cite are day-care problems, long commuting trips and increasing financial stress among young families that have moved farther from Washington to take advantage of cheaper housing.

"Because of the stresses of lack of income, you are going to have more hitting, more abuse, more neglect. You are going to take more chances. Sometimes day care is a luxury," said Tom Michaels, a social worker.

Wanting to illuminate the causes and responses to the sharp increase in abuse and neglect, the Prince William County Department of Social Services agreed to let a reporter go with social workers to visit clients receiving counseling -- most of them young, white and low-income -- with the understanding that the clients would not be identified.

During the visits, the social workers dealt more with issues of poverty and family problems than with the inappropriate punishments or neglect that first brought them to the homes.

In the case of the 22-year-old woman visited by Barbara Cotton, the house is filled with family photos and the den is littered with accumulated evidence of small children, from baby bottles on the floor to a rocking horse and stuffed bear in the corners.

The 18-month-old tries over and over to pull down a glass jar, oblivious to his mother's repeated yells of "no" and "stop." Cotton walks over to the boy and interests him in some coasters as a harmless alternative to the jar, trying to give the mother an example of a better way to handle the situation.

Later, the boy wanders into other rooms, but the mother doesn't notice until Cotton asks what he is doing, an attempt to subtly steer the mother to understanding that a child that age needs to be watched more carefully. The social worker flinches but says nothing when the mother slaps the boy on the leg.

Cotton and the woman search for solutions to the deeper problems, the first being how to look for housing the woman and her husband can afford on their low salaries, hers from working part-time at a fast food restaurant. The social worker gives her ideas on where to look, but low-cost apartments are hard to find in a county where the wait for subsidized housing can be two to three years.

On the pregnancy, Cotton discusses options -- abortion and adoption among them -- but ultimately the woman decides she will have and keep the baby. Cotton said later that the woman wants to be sterilized so it doesn't happen again, but that doctors refuse to do it because she is so young.

"Too many babies!" the woman tells Cotton.

A foul smell wafts out of the three-room shanty, which is understandable since the place has no toilet and the occupants use a free-standing pot or the outhouse instead. There is no shower and no phone. The stove is out, so they cook on an electric skillet. The roof is falling in and the chairs are falling apart.

The woman, whose teeth are discolored from neglect, but who has painted her fingernails pink, stands outside her home and tells Cotton about some of her financial difficulties and her hope that her mentally retarded teenage son can get into another special education group.

As they talk, her son brings over the latest electric bill, which includes a threatened cutoff because she is about $200 overdue.

"We'll have to do without food. I'll use the money from {the boy's} father for the electric," the woman said.

The mother had a job until social workers told her she could be found guilty of lack of supervision for leaving her son alone because, with the mental age of a 5-year-old, he is not capable of caring for himself. She gets about $500 a month in supplemental security income and child support.

Social worker Pam Jepsen catches up with her client, a mother of five, at the dry cleaner where she works days. She also has a night job and must rely on rides with friends to get from one place to another.

Transportation is a particular problem for low-income families in Prince William County, which has no bus service or other public transportation.

This woman's most immediate problem is one social workers see over and over: She doesn't make enough to afford the $800-a-month rent on her apartment. She has been on the waiting list for subsidized housing for two years.

The woman gets no help from her husband, who has alcohol and drug problems and is on the lam after being sentenced to jail. Social workers found he had emotionally and sexually abused some of the children, which is how they got involved with the family.

The woman also needs an operation but has no health insurance and cannot afford the thousands of dollars it would cost. Taking home about $300 a week from her two jobs, she is well over the Medicaid income limit: $6,800 a year for a family of six in Prince William County.

"People ask me if it's worth it, and I say, 'Heck yes, look at them kids,' " she says, despite her multitude of problems. "The kids are everything to me."

Jepson later points out to a reporter the irony of this hard-working woman's situation: If she left her jobs, she could get welfare, health care under Medicaid and free day care for her youngest children when she went back to work.

Another case started because a 12-year-old was put in charge of five younger children, including a sick 8-year-old and newborn premature twins on breathing monitors.

Over the next few years, social services dealt with allegations of physical abuse of the oldest boy, and last year the oldest girl told Cotton that her stepfather had been sexually abusing her since she was 7 or younger.

The father was ordered out of the house, eventually pleaded guilty to the sex abuse and is in prison for it. He will have to undergo therapy before being allowed back in the home or being given visitation rights if his wife follows through with her stated intention of divorcing him.

"If he had had an affair, I wouldn't be able to trust him outside the house, but I can't trust him in the house," said the mother, who could pass for a sister of her children.

With her husband in prison and without a job of her own, the mother relies on supplemental security income for the twins, welfare, food stamps and Medicaid, and has been able to stay in their town house despite a recent eviction notice.

"Physically, mentally and emotionally, it's been a real strain on me. Now I have a sense of peace," the mother told Cotton.

In the midst of these seemingly intractable problems, social workers say their goal is to keep children in their own homes. But sometimes they have to remove children they believe are in imminent danger and place them in foster homes. In fiscal 1990, 113 children in Prince William County were put in foster care, more than double the numbers in the two previous years.

While the caseload is growing, state and local budget problems threaten the agency with severe cuts in money for child protective services. Some cases will have to be referred to other short-staffed agencies, and counseling services to dysfunctional families may have to be eliminated, said Nancy S. Osborne, Prince William County's chief of social work services.

That would result in more children ending up in foster care, including children in cases like the ones outlined in this story, agency social workers said.

Prince William County is only one jurisdiction trying to grapple with a growing child abuse problem. Complaints in Prince George's County rose 27 percent between 1986 and 1990, while Fairfax County saw a 22 percent increase in confirmed or suspected cases in the most recent three-year period. Howard County recorded a 122 percent increase in abuse and neglect reports from 1987 to 1989.

For Barbara Cotton, a social worker for 10 years, the rewards of turning around a troubled family or keeping a child from being removed from his home prevents burnout from the other cases she sees where the problems just don't go away.

"It's mixed," she said. "With some clients there is a sense of 'What good did services do?' That's not true with other cases . . . . When it resolves quickly, that feels real good."