Jan Berenstain, whose personality and art merged in the wise and gentle Mama Bear of the cartoon clan that she and her husband created, died at Doylestown Hospital on Friday of a stroke. She was 88.

Mrs. Berenstain was stricken at her home in Solebury on Thursday. Just two days earlier, she had still been at work in the studio, illustrating two books that will appear later this year, said her son, Michael Berenstain, an artist who has been her coauthor in recent years. The books, which Michael Berenstain will finish, are to be published in December.

Drawing on the experiences of their own family, Mrs. Berenstain and her husband Stan, who died in 2005, used the Bear family - Mother, Father, Brother, Sister - to teach life lessons to youngsters.

Their approach wasn't sophisticated. It wasn't edgy. It was as warm and comforting as a blanket and a batch of cookies, offering solutions to the little crises that every child encounters.

And it was enormously successful. The bears became a brand in a big way, appearing in more than 300 books, with sales of 260 million copies, published in 23 languages.

There have been Berenstain Bears TV specials and a PBS series, software, clothes, toys, an Off-Broadway musical, e-books, apps, a video game, an interactive website. The Bears even became theme-park characters.

"Those bears have helped so many children through so many kinds of challenges that kids face, in such a cheerful and kind of energetic way," said Donna Jo Napoli, children's author (Sirena, The Great God Pan, Treasury of Greek Mythology) and a professor of linguistics at Swarthmore College.

The stories are skillfully told and a pleasure to read, Napoli said. "We're very lucky to have them."

"The Berenstains made a wonderful and lasting contribution to children's literature," said author Jerry Spinelli, whose books include Maniac Magee, Milkweed, and Space Station Seventh Grade. "My wife Eileen and I recall the warm welcome we received in their house years ago. They showed us their studio; it was almost like being in a hallowed place."

Janice Grant was born in Philadelphia on July 26, 1923, and met Stan Berenstain when they were students at the Pennsylvania Museum and School of Industrial Art, now the University of the Arts, in the early 1940s. Jan, as she was known, worked during the war as a draftsman for the Army Corps of Engineers and as an aircraft riveter. The couple married in 1946 after Stan returned from Army service as a medical illustrator.

Their first work was for the Philadelphia Sunday Bulletin in 1946 or '47, Michael Berenstain said. They did spot illustrations for the newspaper's book-review section that showed people reading, he said. Throughout the 1950s, the couple cartooned for a variety of magazines.

After the births of their sons, Leo and Michael, the family moved to Elkins Park in 1950. They lived there until 1976. They began to illustrate the bedtime stories they told their boys, then decided the stories could be the stuff of a book.

The Berenstains published the first of the Berenstain Bears books in 1962, The Big Honey Hunt, under the guidance of Random House editor Theodor Geisel, popularly known as Dr. Seuss.

As the couple worked on their second book, Geisel suggested that they work the name Berenstain Bears into the title, said Michael Berenstain. Thus, the book that would have been known as The Bike Lesson was titled The Bike Lesson: Another Adventure of the Berenstain Bears. And thus was a franchise launched.

"The stories were pretty much drawn from their lives," said Kate Klimo, who edited about a dozen Berenstain books at Random House. "They're very satisfying both for parents and kids."

The books dealt with everyday crises in the lives of children and families: How to deal with new neighbors, how to count your blessings, how to behave with strangers.

The Berenstains "really were collaborators," added Klimo, publisher for the Random House Golden Books/Young Readers Group. "You couldn't tell where one left off and the other began. They loved their work. The studio was their home."

"She was quite a gentle soul with a wry sense of humor," Klimo recalled. "Jan's gentleness and dry humor were a wonderful foil to Stan's more gregarious nature. She was basically a gentle soul."

The Berenstains moved to Solebury in 1976 because their Elkins Park studio was tiny, their son Michael said.

In Solebury, they were longtime friends and neighbors of Jim and Nancy Farley, owners of Farley's Bookshop on South Main Street in New Hope, store worker Kristina Bauman said.

The authors had many book signings over the years at Farley's, but mostly for their parenting books, not the Berenstain Bears books, said Jennifer Farley, who now runs the 45-year-old shop with her sister, Rebekah.

The store always stocks the Berenstains' books but will be setting up a special section in honor of Jan Berenstain, Bauman said.

Rebekah Farley recalled that the Berenstains would tell her about the books they were working on when she was a child. "I read every single one" of the Berenstain Bears books, she added, describing Mrs. Berenstain as "a lovely person."

Michael Berenstain said that his parents "both grew up in the Depression and they had a common-sense approach to things." He recalled that his mother "would always say kids are a lot smarter than parents think."

He said that as a parent, Mrs. Berenstain "was very original. She had her own ideas about parenting. She encouraged creativity."

What was her favorite book?

"She would always say the book she was working on was her favorite," said Michael Berenstain. But she always seemed to also mention Inside Outside Upside Down, a book about concepts for children 4 and up, which the Berenstains wrote in 1968 and Geisel edited.

Mrs. Berenstain is survived by her sons and four grandchildren. Services will be private.