Q. "We are the parents of a healthy, happy, 10-month-old daughter. She has brought such joy into our lives and so increased our capacity to love that we are thinking of expanding our family in a year or two.

"We are wondering about the possibility of adopting an older child, perhaps from a foreign country. However, most of the families we know who have done this have adopted the child as the youngest sibling.

"Can you give us any guidance on whether adopting an older child as the eldest sibling would work out well, and can you suggest any resources on integrating an adopted child into an already established family?"

A. Adoption is an appealing idea, especially when your child is in that idyllic age between 6 and 15 months. All is so right with the world.

It takes the most serious consideration, however. A child without a family of his own has one strike against him and no need for another -- which is what he'd get if you were to adopt for the wrong reasons. The whole experience could sour.

You have to examine your motives as well as your heart.

If, for instance, you think it would be great fun for your child to have a big brother, or a companion, then you should rethink the idea. An adopted child isn't a toy, or a baby sitter, but a person in his own right.

It's also tempting to think that a child is easier to care for when he's weaned or trained or able to entertain himself. This isn't so.

The older a child gets, the more attention he requires. He can take better care of his physical needs, but the psychological ones increase all the time.

The adopted child needs even more tender loving care to make up for what's missed. Make no mistake: He will grow up with a certain emptiness. While he learns that he is special because he is a chosen child, he also knows that two people gave him away.

This doesn't mean the adopted child is warped or withdrawn. Adoption may make him stronger, more loving, more appreciative -- adversity often has those effects -- but there still will be that piece of pain inside which you can never completely assuage.

This pain is examined in Betty Jean Lifton's literate, lucid book on adoption, Lost and Found (Bantam, $3.50), and so is the anxiety of the adoptive parents and the grief of the natural parents. Lifton also describes the choice each adoptee eventually makes -- whether to search for his natural parents or not. It's a step she advocates for the adult adoptee, but only when he feels so compelled to search he can't resist it and so stable he can cope with the consequences. Although the adoptee might be ready for it, you would need a great deal of love and strength to accept this search for what it is -- a need to know one's roots.

This may sound like adoption is a bad idea, which isn't true at all. It's just that a parent has a hard job, and the more a child needs, the harder it is.

It's also hard to add another child to the family, naturally or by adoption. Even the dog gets annoyed when the pecking order is disturbed, so you can expect the baby to be bothered too. And because an older child needs more understanding, and because the adoption won't take place for another year or so, you'll be giving this attention when your angelic baby has become a terrific, terrible 2.

Still, the adoption will work so long as both children grow up with the right to tell you about their feelings: good and bad. There will be some jealousy between them, it's true, but that's a family for you.

The adoption of an older child can be a fine decision, but most adoptive parents seems to prefer the child to be younger than their own, or at least to mesh in age between a younger and older child. If nothing else, a parent knows what to expect.

A child who is adopted from another culture should do well in our cosmopolitan Washington, and even in middle America if he is completely accepted by his adopted family.

Every family combination -- of number, sex, nationality or relationship -- works well for some people, somewhere. Families cope in a thousand ways. If they know their limitations, they can cope very well.