Q.My sweet, adoring, obedient 9-year-old son has turned into a monster!

He won't tolerate a goodbye hug, much less a kiss, and he never fails to say how much I embarrass him, even if we are only with family members in our own home.

He glares at me frequently, speaks sarcastically and often has a sour attitude, then turns around and acts as sweet as he did when he was 8 -- a mere month ago.

When I tell him that his words and actions hurt me, he becomes himself again and acts upset, offers hugs and apologies and promises to think before he speaks. Needless to say, this behavior lasts for all of 10 minutes and then he's horrid again.

Perhaps I should mention that his father, with whom he has a good relationship, is only home on weekends, and his sister, with whom he is fairly close, leaves home in a few weeks.

A.Your son's behavior is neither unusual nor alarming, and it almost certainly has nothing to do with his father's weekly trips or his sister's impending departure. A child often pulls away from his mother at 9 (or from his dad at 11 or 13). Think of it as nature's way to prepare your son -- and you -- for adolescence, when a child must separate from his parents so he can become his own person.

You'll save yourself a lot of heartache if you see this brief but trying stage as another step in his development and not an attack on you. He has emerged from the cocoon of young childhood as self-focused as ever, but he is increasingly aware of others and what they think of him. Surely the little girl in the next row will laugh at his stupid-looking new shirt; Uncle Harry will make fun of him for watching reruns of "Mister Rogers"; and worst of all, his classmates will tease him if they see him getting a hug from his mother.

His embarrassment isn't such a bad thing because it helps him adjust to others, but it can be tough on the family. When a 9-year-old feels foolish, he takes out his hurt on the one person who makes him feel safer than anyone else: his mom.

Although your son's behavior is fairly typical at this age, you still have to tell him that he hurts your feelings when he glares at you or is rude or sarcastic and that he may not treat anyone that way -- including you. And then you should let the matter drop. He will, as you've found, reform for 10 minutes or so and then get surly again.

When that happens, raise your eyebrow and give him your best no-nonsense look instead of another lecture. The less you react to his annoying behavior, the better he will act, especially if you try hard to appreciate his accomplishments.

He may take two hours to tell you the plot of a two-hour movie but he also spends a great deal of time thinking about right and wrong, even if he doesn't talk about it. This is one reason why he is expansive and outgoing one day and introspective the next.

He is instinctively teaching himself to think better too, although he doesn't know he's doing it. Every time a child concentrates on his collection of baseball cards or comic books, he is sorting and seriating and classifying the information in every possible way. This will help him sort and seriate and classify abstract ideas when he's a teenager. A 9-year-old is also learning how to be a team player when he dives into soccer or baseball, and how to work with people and judge them well every time he makes a friend.

Your son's behavior at 9 has surprised you, but a child can only grow if he can change. You can't expect him to be sweet, adoring and obedient forever.

His next stage will be easier to take if you know what's coming. For accurate insights into the minds and the behavior of 10- to 15-year-olds, read "The Roller-Coaster Years," by Charlene C. Giannetti and Margaret Sagarese (Broadway; $15.95). It's excellent.

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