There was no doubt in our minds that Katherine, who turned 4 in August, was ready to leave home. From the middle of last year until the summer vacation, she began each morning by asking me if I was going to work. Then she would plead with me to stay home, so she wouldn't "be lonely." Needless to say, this did not make me feel any better about working than it made the baby sitter feel about sitting.

It was clearly time for Katherine to go to nursery school. The search for the right school was launched, and by 9 o'clock one August morning she was ready for her first admissions interview.

Whatever insecurity she might have had about school vanished minutes after we arrived. She headed straight for the playground, where summer camp was in progress. Unlike the rest of the civilized world, she could not wait for the vacation to be over and for school to start. By last Friday, she had a tote bag packed with pencils, a notebook, and crayons. By Saturday, it occurred to me that she was growing up at an alarming rate.

By Labor Day afternoon, however, I was convinced I would be spared the separation anxiety I had when her brothers went off to school. A friend called with the news that she and her husband had just returned from taking their fourth child off to college. She said she had only wept three times. Separations do get easier, she declared.

By Monday evening, Katherine had repacked her tote bag at least five times. She insisted on taking an apple to the teacher. My son the teen-ager was helping his 7-year-old brother with math at the dining room table. Within minutes, Katherine had pulled a chair up to the kitchen table, emptied out her tote bag and announced loudly, "I am going to study." Then, in a moment unprecedented in the annals of mankind, she looked up with a smile and said, "Thank you for letting me study, Mom."

She couldn't sleep. At 11:15 p.m. she was sneaking into her brother's room, trying to wake him up. At 10 minutes to midnight she was sitting on her bed in the dark, playing. "I'm too excited about going to school," she said. No experienced mother is going to ignore that kind of leverage. "If you don't go to sleep, you can't go to school," I said.

It suddenly occurred to me at breakfast that this child, who has grown up roughhousing with brothers, had never had a proper briefing on how one behaves in civilized society. I know one working mother whose child was expelled from nursery school; it would hardly do to have the same thing happen to Katherine. "Remember," I told her, "not to kick or hit other children and don't yell."

She looked at me, her eyes very solemn. "I promise I won't hit or kick other children and I won't yell."

By 8:30 a.m. she emerged from her bedroom with a tote bag filled with her school supplies, her ragged security blanket, her bear Jason, and the apple for the teacher.

We drove her brother to the bus stop. He was also worried about her venturing into the world. "Katherine," he said, firmly, "don't say any bad words. Okay? Don't say any bad words to the other children."

"I won't say any bad words to the children or to the teacher," she promised solemnly. That possibility had not occurred to him. He gasped. "Especially not to the teacher!" And with a kiss to her, he was gone.

For reasons I shall never know, I spent my first day in kindergarten convinced that my parents had turned me over to a state orphanage. I vowed this would never happen to my children. We spent the rest of the ride talking about school and when I would pick her up in the evening.

She bounded out of the car and within minutes was up in a tree house. A school handout advised parents to remain with the children for a half hour or so during the first days of school. I was fully prepared to spend the next half hour there, making sure she was all right.

Soon the teachers began rounding up the children from the playground and leading them into their classrooms. Katherine hung up her tote bag and sat down, as she was told.

I went over and knelt down beside her, searching her face for signs of separation anxiety. She looked up as I knelt down. "I promise," she whispered happily, "that I won't kick or hit anyone or yell."

And then she kissed me goodbye and patted me on the arm, realizing with the infinite wisdom of a child precisely which one of us was having the separation anxiety.

"You can go now, Mom," she said gently. "I'll be okay."