MOLLY BANG has done it again.
Bang, who grew up in Baltimore and now lives in Woods Hole, Mass., is a master at creating a picture book that is simple enough to captivate a 2-year-old and sophisticated enough to enchant a 5-year-old, not to mention a parent or grandparent.
Bang's latest winner is ''Yellow Ball,'' (Morrow Junior Books, ages 2 and up). In vibrant pastels, Bang tells the story of a yellow ball that is accidentally left at the edge of the surf as its owners play on the beach.
Readers are whisked away with the ball as the tide carries it out to sea, a tiny yellow speck lost against the vast blue. Under a bridge, past the bow of a huge ship and into roiling storm, the ball survives to come ashore on a faraway beach. There a little boy and his mother discover it. Hugging the well-traveled ball to his chest, the boy carries it to its safe new home -- his bed.
Bang won Caldecott honors as the author-illustrator of ''Ten, Nine, Eight,'' and ''The Grey Lady and the Strawberry Snatcher,'' and her other award-winning books include ''Dawn,'' ''The Paper Crane,'' and ''Wiley and the Hairy Man.''
* Another fresh new effort from a well-respected source is ''Piggies,'' by Don and Audrey Wood. The Woods collaborated on ''King Bidgood's in the Bathtub," a 1986 Caldecott Honor Book and ''The Napping House,'' a 1984 New York Times Best Illustrated Children's Book.
This time they have created a book that defines the word whimsy. ''Piggies'' (Harcourt Brace Jovanovich, $13.95, ages 3 and up) introduces readers to the most original set of piggies ever to populate a counting rhyme.
There are 10 little piggies perched on the ends of 10 pudgy fingers, and each page shows them in different poses and costumes, from a long little piggy in a basketball jersey to a hot little piggy in a skimpy bikini. It's hilarious.
Fans of Don and Audrey Wood can keep an eye out for a new musical rendition of ''King Bidgood's in the Bathtub,'' which Harcourt Brace Jovanovich is releasing in October. The cassette -- packaged with the book -- will include six original songs by Carl and Jennifer Shaylen, who also wrote and performed the songs on an earlier musical version of ''Into the Napping House.''
* A rollicking good time is also the order of the day in ''The Birthday Bears,'' by Ruth Gembicki Bragg (Picture Book Studio, $14.95, ages 3 and up). It cleverly begins as a flashback to last year, when a little girl's birthday party is rudely interrupted by dozens of bears.
Polar bears and brown bears, pandas and grizzlies, they all gobble up the cake and ice cream and just make a terrible mess until the little girl and her brother round them up with the help of the police, several zoo keepers and even a few journalists.
The bears, properly admonished, are then free to leave (with ice cream cones in hand). After all that excitement, this year's birthday seems dull. But then the bears surprise the little girl with a return engagement, and a wild time is again had by all.
* A guessing game leads readers through ''Is it Dark? Is it Light?'' by Mary D. Lankford, illustrated by Stacey Schuett (Alfred A. Knopf, $13, ages 3-7). ''Is it square? No, it's round. Is it near? No. it's far.'' The clues roll along until the boy and girl in this book share the answer -- the moon -- with kids from around the world who share the moon in different languages.
Schuett's oil paintings add just the right glow to this simple celebration of a favorite phenomenon.
* If you haven't happened upon ''Sheep in a Jeep'' or ''Sheep on a Ship'' yet, be sure to check out ''Sheep in a Shop,'' by Nancy Shaw, illustrated by Margot Apple (Houghton Mifflin, $12.95, ages 2-5).
This latest adventure in the series takes five sheep on a shopping trip to an old-fashioned general store for the perfect birthday gift. Like its predecessors, ''Sheep in a Shop'' is a lyrical delight: ''Sheep find rackets. Sheep find rockets. Sheep find jackets full of pockets . . . Sheep decide to buy a beach ball. Sheep prefer an out-of-reach ball.''
It's an ideal read-aloud book because adults will enjoy performing it with a flourish. For inspiration, look for the new cassette and paperback package of ''Sheep in a Jeep,'' ($7.95) which Houghton Mifflin is releasing in October.