By JULIE BOSMAN

Picture books are so unpopular these days at the Children’s Book Shop in Brookline, Massachusetts, that employees there are used to placing new copies on the shelves, watching them languish and then returning them to the publisher. “So many of them just die a sad little death, and we never see them again,” said Terri Schmitz, the owner.

The shop has plenty of company. The picture book, a mainstay of children’s literature with its lavish illustrations, cheerful colors and large print wrapped in a glossy jacket, has been fading.

It is not going away ? perennials like the Sendaks and Seusses still sell well ? but publishers have scaled back the number of releases in the last several years, and booksellers across the United States say sales are suffering.

The economic downturn is a major factor. But parents have also begun pressing their kindergartners and first graders to leave the picture book for the text-heavy chapter books.

Publishers cite pressures from parents who are mindful of increasingly rigorous standardized testing . “Parents are saying, ‘My kid doesn’t need books with pictures anymore,’ ” said Justin Chanda, the publisher of Simon & Schuster Books for Young Readers. “There’s a real push with parents and schools to have kids start reading big-kid books earlier. We’ve accelerated the graduation rate out of picture books.” But literacy experts and publishers praise the picture book for the way it can develop a child’s critical thinking skills.

“To some degree, picture books force an analog way of thinking,” said Karen Lotz, the publisher of Candlewick Press in Somerville, Massachusetts. “From picture to picture, as the reader interacts with the book, their imagination is filling in the missing themes.” Many parents overlook the fact that chapter books, even though they have more text, full paragraphs and fewer pictures, are not necessarily more complex.

“Some of the vocabulary in a picture book is much more challenging than in a chapter book,” said Kris Vreeland, a buyer for Vroman’s Bookstore in Pasadena, California. “The words themselves, and the concepts, can be very sophisticated in a picture book.” Some parents say they want to advance their children’s skills with chapter books.

Amanda Gignac, a stay-at-home mother in San Antonio, Texas, who writes The Zen Leaf, a book blog, said her son, Laurence, started reading chapter books when he was 4. Now 6, Laurence regularly tackles 80-page chapter books, but he is still a “reluctant reader,” Ms. Gignac said. Sometimes, she said, he tries to go back to picture books.

“He would still read picture books now if we let him, because he doesn’t want to work to read,” she said. Jen Haller, the vice president and associate publisher of the Penguin Young Readers Group, said that while some children were progressing to chapter books earlier, they were still reading picture books occasionally.

“Picture books have a real comfort element to them,” Ms. Haller said. “It’s not like this door closes and they never go back to picture books again.”