Hannah Plotkin was born well into the digital age, but that never stopped her from getting excited by the arrival of a large, flat envelope with her name on it. “My mom would always be like, ‘You’ve got mail!’ ” recalled Hannah, 13, a seventh grader in Beachwood, Ohio. “And I’d be so excited to open it and see what it was.”

​Hannah knew it was most likely a colorful paperback from PJ Library, a 12-year-old program that mails a free, Jewish-themed book each month to any family raising Jewish children. After dinner, Hannah would curl up on the sofa as her parents read her the new book.

​“We’d be learning about Passover, and then I’d get a book about it,” explained Hannah, whose father, Shalom Plotkin, is a Conservative rabbi. “I remember really trying to impress my dad with my knowledge.”

​Those shrieks of delight, and the father-daughter conversations that ensued, are what philanthropist Harold Grinspoon had in mind when he launched PJ Library—PJ stands for pajama—through the eponymous foundation he established with his wife, Diane Troderman, more than 25 years ago. The goal was to engage Jewish families through books about holidays, heritage, values and Israel.

​But few could have foreseen the program’s impact—not only on the quarter-million families who have participated so far, but also on the once-tiny market for Jewish children’s titles. PJ Library has mailed nearly 12 million books targeted at children ages 6 months to 11 years since 2005 and runs programs in 12 countries, transforming an industry as it redefines Jewish books for a more racially, geographically and spiritually diverse era. (A separate program targeted at Israeli preschool classes has delivered an additional 11 million books since 2009.)

​“What they’ve done is amazing,” said Joanna Sussman, publisher at Kar-Ben Publishing, a Minneapolis-based Jewish outfit that is the country’s largest publisher of Jewish children’s books and supplies about a third of PJ Library’s annual titles. “They’ve positively and dramatically energized the entire world of Jewish children’s literature.”

Industry insiders say there is no specific sales data for this genre, but PJ’s volume offers a clue to what those experts all point to as the dominant force in Jewish children’s publishing. A typical successful children’s book has a print run of 5,000 to 10,000 copies; PJ Library, in contrast, usually orders about 25,000 books at a time, giving it the power to effectively shape the market.

​With some 200,000 free books mailed each month—some 180,000 of them in North America—the program is uniting a generation of Jews worldwide through a shared literary canon. From Saskatchewan to Singapore, most children in a given age group receive the same titles. “They’re getting Jewish books into the hands of families and children who might never have thought of buying Jewish children’s books,” noted Sussman.

​The Flisses of Seattle are one of those families. Jennifer Fliss is Jewish; her husband, Tim, is not. PJ Library books are central to the non-affiliated couple’s efforts to raise their 3-year-old daughter, Gillian, as a Jew in a largely non-Jewish region.

​Jennifer Fliss, a writer originally from New York City, cites as favorites titles like Grandma Rose’s Magic, written by Linda Elovitz Marshall and illustrated by Ag Jatkowska, about the way a seamstress’s handiwork unites her Jewish community, and First Rain, written by Charlotte Herman and illustrated by Kathryn Mitter, about the bittersweet reality of making aliyah as a child. These books “have been the best way to introduce Judaism to my daughter in a way we are comfortable with,” she said.

Winnie Sandler Grinspoon, president of the Harold Grinspoon Foundation and the founders’ daughter-in-law, said PJ Library falls into a “sweet spot” for modern families. “We’re providing what people are looking for anyway,” she said, “to read great stories to their children and to create strong family traditions and special moments.”

Sandler Grinspoon said PJ Library had its origins in a family Passover seder, when her father-in-law watched his grandchildren light up over the kind of Jewish books the 88-year-old philanthropist never had growing up poor in Newton, Mass., before he made his fortune in real estate. Already a sponsor of the Western Massachusetts chapter of Dolly Parton’s Imagination Library program, which sends a monthly book to area children, Grinspoon decided to create a Jewish book distribution series. The initiative quickly expanded from subscribers near the foundation’s headquarters in Agawam, Mass., to 200 communities throughout the United States and Canada.

​“When you start a family, that is the moment when a lot of people stop and think: ‘What traditions and values am I passing on to the next generation?’ ” observed Sandler Grinspoon, herself a mother of three. By helping spur those conversations, PJ Library books have an outsized impact on the 40 percent of subscriber families in North America with a parent who did not grow up Jewish, and the roughly one-third who are unaffiliated, according to a recent user survey.

“We’re helping many of the families learn along with their children,” said Sandler Grinspoon. Parents sign up for the free program through their local chapter on the PJ Library website—connecting not only to books, but also to other Jewish families and events through outreach programs that build upon the PJ Library network.

To bring books to as many communities as possible, the foundation counts on thousands of donors and seeks out local partners, often Jewish federations, to share the costs of the books and the engagement programs.

For Canadian Reisa Klein, who recently moved from Ottawa to Edmonton, Alberta, with her non-Jewish husband and young daughter, PJ Library provides not only books, but also connection. “Moving here, I really didn’t know anyone or anything in the Jewish community,” said Klein, a postdoctoral fellow who said PJ books help her raise her 4-year-old daughter, Wren, with Jewish values.

Klein has befriended other Alberta Jewish parents through PJ Library’s “Get Together” grant, one of several engagement grants available in selected areas. “PJ Library gave us an in, and that’s pretty remarkable,” Klein said.

​Teaming with global partners, PJ Library itself found an “in” with a new generation of Jewish readers, bringing culturally appropriate titles to youngsters in Latin America, Europe and beyond. In 2011, the program launched in Australia; English titles are also mailed to the United Kingdom and Singapore, where 36 mostly expat subscribers clamor for PJ books.

Translation beyond the English-speaking world presents challenges both literal and metaphorical, said Alex Zablotsky, PJ’s director of operations. In six Latin American countries, where mail is unreliable and local affiliation strong, the program distributes Spanish books at local Jewish community centers and Jewish day schools, in partnership with the Universidad Hebraica in Mexico.

​In Russia, native as well as translated titles are important for recipient families. “We want to make sure it feels like a Russian program, it doesn’t just feel like an American export,” explained Zablotsky. And the Hebrew-language sister program, Israel’s Sifriyat Pijama, which sends some 340,000 books a month to Israeli classrooms, has an enthusiastic partner in Israel’s Ministry of Education.

​In America, the past decade has seen PJ book programs expand to schools and summer camps. More than 20,000 grandparents signed up last year to receive mailings that range from grandparent-themed books to Rosh Hashanah recipe cards for their grandchildren. (The grandparents’ program is ongoing, but is currently being limited to existing subscribers.)

​And when the original cohort of readers outgrew the core program at age 8, the foundation launched PJ Our Way, which lets 9- to 11-year-olds choose from a selection of young adult titles.

​The process of choosing books is extensive. Every month, PJ’s book selection committee—a dozen authors, editors and Jewish educators—gathers to mull upcoming titles. Suggestions include classic and contemporary works, even not-yet-published books. Some titles begin as manuscripts solicited by PJ Library, which then shepherds them through the publication process—either in collaboration with an outside publisher or in-house, as one of the five to 10 annual books produced by PJ Publishing, a two-year-old operation. Manuscript submissions have grown fourfold since 2012, and to further expand the field, the Grinspoon Foundation sponsored its first annual workshop for writers of Jewish children’s literature this past summer at the Yiddish Book Center in Amherst, Mass.

​For authors, PJ Library has opened up myriad opportunities. “Certainly my books are getting into many more hands than they did before PJ Library,” said Northampton, Mass.-based author Richard Michelson, who has had several titles distributed by the program, including his 2016 Fascinating: The Life of Leonard Nimoy, a reader hit illustrated by Edel Rodriguez.

Being a PJ Library author “raises your profile,” said Michelson. “Publishers are more likely to take a risk if they know PJ is interested. And it’s easier for a mainstream publisher to take on a book that might have narrower appeal.” As an example, he cited his most recent PJ title, The Language of Angels (illustrated by Karla Gudeon), about the renaissance of spoken Hebrew.

Audrey Mitnick, a sales manager for Sleeping Bear Press, which has published several of Michelson’s titles, confirmed that a PJ connection helps non-Jewish publishers find their way into the Jewish marketplace. “I always feel there is some hesitancy in the marketplace because we are not a Jewish publisher,” said Mitnick. “PJ Library removes that in the minds of some buyers.”

Larger publishing houses rely less on the PJ lift to make or break sales on a Jewish-oriented title, said Michelle Frey, executive editor at Knopf Books for Young Readers, which is part of Penguin Random House and also has published Michelson’s books. “Ultimately, the advantage is exposure for the author and for the book,” she said. “We know month after month and year after year, PJ is taking these books that might otherwise be sitting on the bookstore or library shelf and putting them into the hands of children, making them into books that are read again and again.”

​The program’s vast readership also expands opportunities for new authors like Sharon Reiss Baker, a former elementary school teacher and high school administrator from Bala Cynwyd, Pa., who had one published book under her belt before submitting her second manuscript to PJ Library.

Baker’s 2014 PJ title, All Kinds of Strong (illustrated by Kris Wiltse), tells the story of a frail but emotionally resourceful child who rallies her Jewish farming community after a fire destroys the local shul. It incorporates themes that are historically underrepresented in Jewish literature: disability, agriculture and rural life.

“That’s what I love about PJ: the breadth of what they understand to be a Jewish book,” said Baker, who added that the explanatory flap notes—a staple of every PJ book—illustrate how All Kinds of Strong exemplifies the Jewish precept of being responsible for one another.

With diversity a priority across contemporary children’s literature, PJ Library consciously aims to “reflect the diversity of Jewish lives and practices,” said Meredith Lewis, PJ Library’s director of content and engagement. In PJ books, that can take many forms: Asian and black characters, Sephardi as well as Ashkenazi stories and highly varied illustration styles.

Consider a recent hit among 3-year-olds, as measured by reader feedback. The Night World, written and illustrated by Mordicai Gerstein, portrays the nocturnal adventure of a boy and his cat as they watch the sunrise; the opening quote from Genesis prompts readers to consider everyday experiences from a Jewish perspective.

So what, exactly, makes a book Jewish? Titles like The Night World and Fascinating: The Life of Leonard Nimoy are a far cry from the Jewish books many parents grew up with, which largely revolved around the shtetl or immigrant experiences. Another time-honored topic, the Holocaust, is a PJ Library taboo for the younger set because, Lewis said, parents should decide when to introduce such a topic.

​While some chafe at the proscription, “having that policy really opened up a lot of other underexplored areas, because the Holocaust was so overrepresented, even in books for very young children,” observed Jodi Eichler-Levine, who has studied the PJ Library phenomenon as the Berman Professor of Jewish Civilization at Lehigh University in Bethlehem, Pa. “Now, they’ve got lovely and fun books about knitting and trees.”

Such themes “reflect the fact that for many Jews today, a Jewish practice isn’t necessarily something that takes place in an institutional setting,” Eichler-Levine added. Today’s youngsters, according to PJ surveys, are drawn to themes that resonate with contemporary lives, like the environment (for Tu B’Shevat, PJ has also sent seed packets) and politics.

While PJ Library aims for inclusivity, Lewis acknowledges that there is no portrayal of Jewish life that will represent everybody. In creating a modern Jewish canon, her team looks for the same literary elements that set a higher standard for secular books while focusing on “commonalities, the joy of Jewish life,” rather than religious detail.

The attempt at a wide appeal has led to criticism in some quarters that PJ books are “Judaism lite,” said Rachel Kamin, who edits children’s book reviews for the Association of Jewish Libraries Newsletter and is the director of education at North Suburban Synagogue Beth El in Highland Park, Ill. “PJ wants to be one size fits all, and that’s a challenge,” added Kamin. “They’re trying to pick books that will work for everyone and not upset anyone.”

​They haven’t always been successful. Most notably, a 2013 PJ selection featuring gay parents—The Purim Superhero, written by Elisabeth Kushner and illustrated by Mike Byrne—caused controversy when PJ decided to distribute it only to families who requested it.

​But many Jewish parents say PJ Library strikes just the right note. Yosefa Bankhalter, a teacher and mother of seven who is a member of Brooklyn’s Lubavitcher community, calls PJ books “kosher; I would say pareve.” She subscribes in order to supplement her children’s yeshiva education with poetry, good English writing and beautiful artwork. “My son studies Gemara for I don’t know how many hours a day, and at night he can lie in bed with a book and let his imagination roam,” said Bankhalter.

Like any industry disrupter, PJ Library has raised concerns within the book world—over the potential for Jewish writers to limit their scope to “what PJ is looking for,” or for the devaluation of Jewish books now that so many are free, noted Kamin, who served on an early PJ Library book committee.

But plenty of Jewish books still do sell, and there is evidence that a growing readership is diversifying the market. Apples & Honey Press, a Jewish children’s book imprint from Behrman House, launched in 2015, giving Kar-Ben competition in a market it had long dominated. Several small Orthodox imprints also release Jewish children’s literature, but for a much more focused audience.

“We are, after all, the People of the Book,” reflected PJ Library’s Lewis. “Judaism has been telling the same stories over and over again for millennia, with each generation adding chapters and putting its own spin on those stories. I think PJ Library is part of that tradition.”

Hilary Danailova writes about travel, culture, politics and lifestyle for numerous publications.