“It used to be when a class would come in,” Taylor said, “I’d have a line of 10 kids that needed to ask me, ‘Where’s this book?’ Or where’s this or that.” After genrefication, she said, “some periods came in, and there wasn’t one kid that needed to ask me anything, and they all found books in half the time.” A child who previously floundered “went right over to the Humor shelf, and it took about 30 seconds,” she added.

Genrefication is also said to highlight usage patterns and gaps in inventory, allowing librarians to better tailor their offerings to students’ needs. Taylor was able to purge a third of her collection as she discovered just how many books fell into categories the students didn’t care about; she also realized McCaffrey had far too much Fantasy and not enough Adventure. Blogging on “Beyond the Shelves,” Christy Minton tried to rally other librarians: “Instead of purchasing books that you think your patrons will like, why not start ordering books you know teens will love!” Data-informed curating doesn’t just serve kids better, Minton pointed out; it’s a savvy play in a school climate where budget-cuts rein: “A busy library is a funded library.”

Librarians wield circulation statistics to support their claims of genrefication success. Leigh Collazo, otherwise known as “Mrs. Reader Pants,” reports a 36% increase after she genrefied a middle school library in Fort Worth, Texas in 2011. The team of librarians at New York City’s Ethical Culture Fieldston School also reported “dramatic increases in circulation” in a School Library Journal article entitled “Are Dewey’s Days Numbered?”

Though data on how widespread the practice is aren’t readily available, Tamra Marshall, a certified teacher librarian at Rooftop School in San Francisco*, said the notion that genrefication may be better is “the current thinking in the school librarian world.” But Marshall hasn’t yet tackled the project because, as she put it, “We just do not have the man/woman-power to take on a switch, especially since most schools only get a part-time librarian.” In a popular 2013 article Jocelyn Sams elaborated, “I have a full schedule of classes on most days, and I don’t have an assistant. I can barely get my books shelved in a typical week, let alone redo thousands of labels and change the online catalog.”

Some take advantage of a transition, like Taylor who sorted her collection during a three-week winter break and then completed the project over the following month with help from another staff member and a few students (plus about $500 for new labels). Collazo said she worked on the reorganization alongside an aide and about 10 eighth-grade students a little each day for four months. Others report shortcuts like using books’ copyright pages or Goodreads listings to quickly select a genre. But there’s no question that time and effort stand as barriers to implementation.

The Dewey-loyal also oppose genrefication in principle for, interestingly enough, the same reason others support it: self-sufficiency. Sure, they argue, kids might be better able to find a book independently in their school library, but what happens when they go to the public one? When they get to high school? Each library shelving books according to its own system is exactly the problem Dewey set out to fix, and it’s one that’s particularly problematic for high-mobility kids who move from school to school, they say.

That’s why the American Association of School Librarians hasn’t taken an official position on the “white-hot” topic, said its current president Steven Yates, despite “spirited discussion” at the group’s biennial conference and in the “Dewey or Don’t We” issue of its print magazine. “It really comes down to meeting your community’s needs,” he said. In a school with a fixed schedule and generous amount of library time, for example, “there’s time for a lot of library-skills instruction,” and in that setting, he said, “Dewey can be something that can be a lot easier to adopt.”

Even then, the New York City librarians wrote: “Having moved away from an old system of organization that demanded that a significant portion of our teaching time was spent on simply finding books, we’re now able to concentrate on talking with our students about books, as well as teaching them critical thinking and assessment skills.” So the decision could come down to a pragmatic consideration of resource availability and student body composition, but it might also touch the soul of the field: What ought the core mission of a modern school librarian be?

The debate has led to compromise positions. Some leave books for older students in the Dewey arrangement while genrefying for younger ones. Other librarians rearrange middle readers and young adult books but leave picture books shelved by author since it can be unclear how to categorize a story about a duck driving a tractor. (Animals? Transportation? Fantasy? Librarians have gotten creative with multifaceted books such as "Twilight" which qualifies as both Romance and Paranormal. Some report letting students vote at the get-go; others assign a genre and then encourage kids to lobby for a switch.)

Collazo took things in the other direction. She de-Deweyed many of her nonfiction books as well, moving, for example, Parapsychology and Occult to sit alongside scary fiction books: “Students didn’t tend to find the 133 section before, but boy do they find them in the Horror section.” That’s a move others who genrefy say better aligns libraries with the Common Core curriculum.

Back in Galt, Taylor’s new classifications continually evolve. What she initially dubbed Drama morphed “basically into Chick Lit,” and she created a small shelf dedicated to the Holocaust, a focus of school assignments at McCaffrey. Each change is made with one goal in mind, she said: “So they don’t waste a week reading a book that they end up not liking and can’t finish.”

“I really try not to come down on any one side,” AASL’s Yates reiterated, but then added, “I just think that I’ve not seen people that’ve gone to genrefication then go back.”