One of the great disappointments of parenthood comes when a son or daughter greets a favorite childhood book with, at best, disinterest, or, at worst, disdain. Some children's books are better remembered than read, while others continue to enchant young readers for generations.

Virginia Haviland, chief of the Children's Literature Center at the Library of Congress, reads nearly all of the 2,000 children's books published in the U.S. each year. A good book for children, like a good book for adults, she insists, "has something to say and says it with style."

Adults who buy children's books tend to lean heavily on the classics, she says, "but times change; sentimentality doesn't have a place today. There are plenty of modern classics which should have their chance."

A bookseller who is knowledgeable about juvenile literature can offer valuable suggestions about purchases, she says, but such people are rare in the "supermarket" bookstores becoming common today.

For book-giving she advises parents to begin their search in the local library. "A good librarian knows what goes," she points out, and should be able to suggest titles which children will enjoy rereading, a quality worth considering in the face of rising book costs.

Before joning the Library of Congress in 1963 to establish the Children's Literature Center, Haviland was the Readers' Adviser for Children for the Boston public libraries. She regrets that her current responsibilities do not include daily contact with youngsters.

"I miss my guinea pigs," she says. "It was tremendously satisfying to find that the children liked what I thought they would like."

Many libararies offer lists of selected books for various age ranges on subjects popular with children. The Library of Congress also publishes an annotated list of 200 of the best books published each year. The current list, "Children's Books -- 1978," is available through the Government Printing Office.

Award-winning books often are a good bet for strangers to children's literature. The Newberry and Caldecott Awards are given annually by the American Library Association and the National Book Award includes a children's literature category each year. Dust jackets or covers usually note any awards won by a book.

Award-winners, however, "are not necessarily best sellers," Haviland says. "But they have an audience among children with, let us say, discretion."

Popular series books, like the Bobbsey Twins, are not among Haviland's favorites. "They're all alike. They don't help a child to become adventurous; they encourage lazy habits.

"A child knows what he likes, but he doesn't kow what he's capable of liking." As in the case of a new food, a book which appears different or which does not look inviting may have to be "properly introduced" to a skeptical youngster. She suggests beginning a book by reading it aloud to encourage a child to continue a new book on his own.

In fact, many children's books when read aloud can be enjoyed by everyone from pre-schoolers to parents. Children are able to appreciate stories on a level far above what they are able to read. She suggests collections of stories which can be finished in one sitting as good choices for reading aloud.

The look of a book -- its cover, format, even typeface -- can greatly influence a child's reaction to a book. A book with plenty of leading, or space between the lines, for example, looks easier to read than one in which the pages appear crowded.

Older children with more pronounced individual interests are more particular than younger readers, says Haviland. Biographies of sports personalities or historical figures, folk tales, and nature and science books begin to become popular with readers from about grade 4 and above.

Many old taboos, particularly in literature for older children, have gone by the wayside. Subjects such as death, divorce, broken homes and suicides, once forbidden in children's books, are commonly handled today. Haviland believes that television is in part responsible for the change: What might have once been considered shocking is standard fare on TV.

Books for younger children rely as heavily on good illustrations as on the story for their success. Although most illustrations are as appealing to parents as to children, adults are not always the best judges, Haviland points out.

When "Where the Wild Things Are," a Caldecott prize-winning book by Maurice Sendak (Harper & Row), first appeared, some parents and teachers thought that its illustrations of horned and clawed fantiastic creatures would frighten young readers. The book continues to be a favorite with youngsters

Shopping for a book for a child -- whether pre-schooler or pre-teen -- requires a bit of guidance and some imagination. The right book, be it an old classic or a recently published introduction to particle physics, can be as rewarding for parent as child.