Kate Messner was the first writer to take the leap from supporting the #WeNeedDiverseBooks hashtag to choosing a particular title to get behind this spring. “Speaking up is one great way to ask for change,” she blogged late last month. “But buying books may be an even better way. At the end of the day, publishing is a business that needs to make money to survive. Given that reality, the best way for readers to ask for more diversity in children’s literature is not with words and tweets and blog posts alone but also with dollars.”

Messner wrote that she had pre-ordered two copies of Varian Johnson’s The Great Greene Heist (to be published May 27) from the Flying Pig in Shelburne, Vt., and wanted to make it a New York Times bestseller. She called for others to join her in supporting their local independent. Her post was game-on for two Massachusetts booksellers, the Odyssey Bookshop in South Hadley and Eight Cousins in Falmouth. “Support diversity in children’s fiction and help show Eight Cousins that nobody can beat the phenomenal customers of Odyssey Bookshop and community of the Pioneer Valley,” wrote the Odyssey on its website. In reply, Eight Cousins updated its glowing review of Johnson’s book and added: “I hope you will purchase a copy of The Great Green Heist at whatever your local bookstore happens to be because it’s awesome and because diversity in kids’ books matters. But I also hope you will consider pre-ordering it at Eight Cousins to help us kick Odyssey Books in the pants win the challenge.”

Author Shannon Hale stepped in and proposed opening up those two stores’ handsell-off to the community at large. Since then dozens of booksellers have signed on to participate in the #GreatGreeneChallenge, which runs through June 30. In part, because it’s such a fun book to get behind: PW’s review called it “an exciting Ocean’s Eleven-style caper for the middle-school crowd,” and Eight Cousins publicity and program manager Sara Hines noted that it’s a book that “deserves all this attention.”

When Valerie Koehler, owner of Blue Willow Bookshop in Houston, read Hale’s Tumblr, she immediately challenged her friend Sarah Bagby, owner of Watermark Books and Café in Wichita, Kans. “Besides the fun of a contest, which many of us love, it will be a great introduction to a wonderful new book,” said Koehler. “Varian is on our long list for authors being proposed for our area’s Tweens Read Book Festival in the fall.” Like many handsell-off participants, both are still in the brainstorming stage, but expect to get off an e-mail blast to educators in the coming week. Heather Duncan, director of marketing at Tattered Cover Book Store in Denver, said that her store also wanted to participate in this grassroots effort to encourage diversity in literature. She’s still in the planning stages but is looking at social media outreach now and in-store signage when the book is available later this month.

Other booksellers, like Anne Whaling, children’s book buyer at Mrs. Dalloway’s, said “yes” as soon as they saw Kate Messner’s challenge, because they see it as an opportunity to nudge publishers to catch up with the store’s customers of all skin tones. “We were already walking down that road,” said Whaling. The store’s annual mid-May program for teachers, parents, and students, Hot Reads for a Cool Summer, will focus on books with kids of color and includes a panel on diversity with authors Mitali Perkins and LeUyen Pham and librarian Nina Lindsay with the Oakland Public Library.

But it’s not just bookstores that are signing up for the challenge. So have authors. To date, prizes for stores that sell the most copies of The Great Greene Heist range from a free Skype writing workshop with Messner to prints donated by Grace Lin, and signed books from John Green, Skila Brown, Ally Condie, Janet Fox, and Karen Sandler.

“It’s been amazing to see the support from authors, readers, booksellers and others in our community,” Johnson told PW, “and I’m humbled by each and every bookstore that has taken the #GreatGreeneChallenge. When I began the novel, I was only trying to write a fun caper that featured a diverse cast. Every author hopes that people will read and champion his or her work, but it’s not something you can plan for.”

Johnson’s editor, Cheryl Klein, executive editor of Scholastic’s Arthur A. Levine Books, said that her company is “thrilled” that booksellers are getting behind the book. “From the moment I got the manuscript, I believed this was a book that could and should reach as wide an audience as possible. Here’s hoping many more readers join Gang Greene!”

Scholastic is supporting the challenge by expanding its efforts on behalf of the book, which already included a major galley mailing and appearances earlier this spring at Children’s Institute and the Texas Library Association. It added a merchandising kit for booksellers, which includes a shelftalker, a letter from Johnson, bookmarks, signed bookplates, and buttons marked, “Ask me about the #GreatGreeneChallenge.” It’s also upping its social media outreach and industry advertising, plus it is promoting the prequel excerpt, which is available on Johnson’s website.

In addition, Johnson is personalizing books for his two local indies in Texas, The Book Spot in Round Rock and BookPeople in Austin. The latter will also provide a signed copy of The Kelsey Job, the prequel to The Great Greene Heist, with each book sold.