Q. My son, nearly 3, gets extremely anxious when I leave him with anyone except his regular baby sitter. She stays with him at his play group, but she won't be able to do this when I start working again, since we have a new baby.

If we leave him -- and this has almost always been true -- he will scream until the sitter or I return, and he has the stamina, and the intention, to keep it up for one to two hours. It's almost as if he can't stop once he starts, and the noise is ear-splitting.

Otherwise, he's a big, healthy, exuberant child who eats well, takes a two-hour nap, goes to bed without much fuss and plays happily with his little friends several days a week, either when I take him to visit them or they come to our house.

He has been in his twice-a-week co-op play group for 12 children at a neighborhood center since he was 21 months old, but has only stayed there alone for about eight weeks, when he was 2 1/2. When he cries, the sitter or I play with him there for a while, then bring him home, since it would only reinforce his behavior if we went back to pick him up when he cried.

We've even been to a counselor who thought that he might have trouble perceiving his body in space -- she said it could make him insecure -- or that the prospect of a new baby may have frightened him, and he began to fear that we might give him away.

I spend about eight days a month working out of the house, on an irregular schedule, and about nine days a month in my home office, taking frequent breaks to play with my son. To me it's the best of both worlds. I have a challenging career -- I could have been born for it -- and a family I love.

And I'm a happy, optimistic person who thinks this problem has a solution somewhere but right now I'm at my wits' end.

A. Every child is different -- in looks, in abilities, even in fears. While most children find it fairly easy to say goodbye to a parent, your son does not. And while most children get a kick out of play group, he finds it overwhelming.

These are real concerns and they need to be honored.

There really isn't any reason for your son to go to that play group, or, indeed, to any play group now. Casual, regular meetings of four or maybe eight children are just the ticket for some pre-3s, but most young children would rather see their playmates at each other's houses, or in the park.

Even if your little boy is ready for a play group or a nursery school now -- and many 3-year-olds are not -- the co-op has soured that experience for a while and added to his general anxiety.

He can get his self-confidence together a lot quicker if he quits any formal structure for a while, so his sense of independence won't be tested, week after week. Children know when they fail, and they can't build success on failure.

Once your son quits the play group, he should begin to feel safer. This -- and some special treatment -- should make it easier for him to stay with other sitters, but you may have to change your own habits first.

Good parents have a thread in common with each other. They are so instinctively in tune with their children that they respond to their most subtle signals.

This is ideal, but it can lead to problems.

If a child is a little anxious about eating or sleeping -- or being left in a play group -- the very perceptive parent might respond too much, which only heightens his anxiety. You can see why. If the parent is worried too, there really must be something to worry about. It's a cyclical situation.

You'll be more effective if you -- and the sitter -- can relax a little. Your little boy needs you to adopt the same breezy, positive approach with him that you show to the rest of the world, but you'll have to get him used to other sitters first.

First hire one or two other sitters just to visit and to play with your son, while you or the regular sitter is with him too. After a few times you should be able to leave him with these new people, if they, and you, are willing to put in a hectic week or so to change the scenario.

Have the regular sitter take the baby out for morning and afternoon walks, and arrange for a replacement sitter to come over after she's gone, so your son can adjust to change in the safe environment of his own home, while you work in your office.

Instead of staying with him when he cries, however, just give him a hug and a ruffle of his hair, then go about your business -- your way of telling him that he'll be just fine.

He'll cry again, of course, and you'll comfort him in 5-10 minutes, but then you go about your business. And he'll cry, you'll return, give your quick reassurance and leave, time after time, so he'll begin to realize that you always come back, and that it's no big deal.

By scaling back your reactions, he'll begin to temper his own, and then he can afford to be daring. Life is really an adventure, but first a child must learn that the road is safe, even when his parents aren't around. Questions may be sent to P.O. Box 15310, Washington, D.C. 20003.