Some parents, despite the pain of separation, are happy with the services they receive.

Other families confront a host of difficulties. They enter a world unaccustomed -- and, some insist, hostile -- to parents who take an acute interest in their children's care. But the biggest frustration, parents say, is that giving up custody does not guarantee that their children are kept safe or given adequate attention.

The money to provide mental health treatment in foster care is actually very limited. Often, said Harriet Mauer, the director of social work for Good Shepherd Services, a foster care provider in New York City, foster care facilities must turn to the same overburdened community mental health clinics that parents do. Often, a determining factor in treatment is simply the availability of an open bed.

''They push the parents to give up the kids, and I don't understand why, when they don't have the care that they need,'' said Kathryn Strodel, a lawyer at Legal Services of Central New York, in Syracuse, who has represented parents who have relinquished custody.

A Child With Autism

Daniel is a 16-year-old, 200-pound autistic boy with an emotional disorder. He sometimes pretends that he is the Incredible Hulk and tries to rip off his clothes in public. There are dents in the walls of his mother's Bronx apartment from his punches. More than once a week, his mother said, she needed to call the police for help. ''This is a child,'' she would say when she thought they were handling him roughly.

Daniel would be taken to the hospital, calmed, and discharged.

Agencies that deal with autism said they could not help for a variety of reasons. The mother's sister grew afraid to baby-sit.

The mother, who insisted that the family's name not be used for fear of retaliation against Daniel, said ''I've used sick days, vacation days, personal days and leave without pay to do what I've done with this kid.''

At the hospital, she said, she had been regularly told by doctors and social workers that the only way to get help would be to leave her son there, so that she would be reported for abandoning him and the state would take custody.