IT WAS A SATURDAY, midmorning. A telephone split the stillness.

Kendall McArthur's adoptive mother, Dorothea, known as Dorrie, took the call in the study. In an instant, more than two years of turmoil crested, then crashed in Kendall's heart. It was her birth mother.

Kendall, 11, dismissed a playmate. She crept to the study door, just out of sight, and listened intently. Within moments, the conversation grew heated. Kendall had neither seen nor spoken with her birth mother, Patti Sheets, in what seemed like forever.

There was biting anger in Dorrie McArthur's voice as it tumbled out of the study and into Kendall's elegantly appointed Silver Lake home. Kendall caught every word, and she filled in the silences with good guesses about what her birth mother was saying on the other end: I want to see Kendall.

She thought this might happen. Her birth mother had called three weeks before, for the first time in 27 months. She had spoken with Dorrie — but not with Kendall, who had been deeply hurt by her absence. Kendall had already insisted on conditions for a visit: Patti must see a psychologist, just as Kendall was doing. She must figure out why she had disappeared from Kendall's life. She must explain it, and she must promise never to vanish again. Barring that, Kendall said, even if Patti appeared at her door, she would hide in a closet and refuse to see her.

On the phone in the study, Kendall's adoptive mother was spelling this out again. Last time, the conditions had met with stony silence. Now there was fury.

Maybe it was over. For six years, Kendall had been in an open adoption, a delicate arrangement by which children see their birth parents often — at least several times a year, sometimes weekly, even daily. By agreement, both sets of parents — adoptive and biological — play large roles in their children's lives.

Forty years ago, most adoptions in the United States were closed. Today, about 25% are completely open. Most of the rest are at least partly open, with varying degrees of communication between birth families and adoptive parents. But the arrangement can be contentious. Some adoptive parents fear that bonding with children will be harder if birth parents are around. Others are convinced that children benefit if they know their birth parents well.

Kendall's adoptive parents, Dorrie McArthur, a practicing psychologist, 52, and her husband David, 48, now an epidemiologist engaged in brain trauma research at UCLA, wanted this adoption to be as open as possible. Ever since Kendall could remember, open adoption had forced her to struggle with both of her families. At the same time, however, it helped her understand her roots. More important, it was showing her that being adopted was not her fault.

Nonetheless, Kendall was afraid that she might be rejected again, by one set of parents or the other, and her birth mother's disappearance for the last two years had not helped. During that time, Patti Sheets had rejoined the Army, become a Patriot missile operator at Ft. Bliss in El Paso, and prepared to divorce for the third time. If this open adoption was going to work, Spc. Sheets, 34, had to promise to stay in touch.

As Dorrie McArthur set out Kendall's prerequisites for a visit, Patti exploded in anger. One thought raced through Patti's mind: I'm not buying Dorrie's bull. "You're a shrink," she said. "You know how to play shrink games, and I want to see her before I go."

Dorrie recalled replying tartly that Patti was the one who had disappeared. It had hurt Kendall, and it had wiped out the benefits of open adoption.

Kendall, deadly quiet, listened.

Patti retorted: If Dorrie wanted an open adoption, she had to consider Patti's feelings and needs as well as those of her other children. Patti would not reopen the adoption on what she considered to be Dorrie's — not Kendall's — terms. She would see Kendall on neutral ground in a public place: Wild Animal Park in San Diego County, where Patti was visiting her father and her mother. No therapy. Take it or leave it.

Dorrie said she had the legal rights to Kendall.

Kendall sensed that her adoptive mother was about to hang up. She might never see her birth mother or her half-brother and half-sister again, and she would miss them terribly. Quickly, she stepped out from behind the study door. She shook her head violently and mouthed three words.

Dorrie could not understand.

Kendall was frantic. She seized a piece of paper and mouthed the words again. She held up the paper so her adopted mother could see.

"Let her come."