A pilot program between the world's largest circulating library and the nation's biggest public school system is allowing New York City teachers to borrow books online and have them delivered directly to classrooms for the first time.

The school system's partnership with the New York Public Library—set to be announced Monday—lets teachers at more than 50 schools borrow up to 100 books at a time, including sets for an entire class, officials told The Wall Street Journal. The schools' students also will get library cards.

At P.S. 63, the school shares a library—and librarian Cheryl Wolf—with the other school in its building. Ramin Talaie for The Wall Street Journal

"What this offers students is access to a world of resources well beyond what their school library can stock," said Gregg Betheil, the Department of Education's executive director for school programs and partnerships.

The project started a few weeks ago and comes as the city has cut school librarians and assistance for teachers to buy supplies. Library and city education officials said the program, called " Biblio Schools," isn't meant to replace school librarians.

Anthony Marx, president of the New York Public Library, said he hoped to find funding to expand the program to every city school within two years.

"Not only do we not want to replace school librarians, we want to give them the resources that will make their jobs possible," he said.

The pilot includes schools in Manhattan, Staten Island and the Bronx, which the public library serves. It doesn't include schools in Brooklyn and Queens, which have separate public library systems.

Under the program, teachers and students are now able search their own school library as well as the New York Public Library using a new online catalog called BiblioCommons. It allows all readers—including students and teachers—to post reviews of books and share book lists.

Teachers who said they often have to spend their own money on classroom books, especially after a subsidy was canceled this year, said the opportunity to borrow class sets could save them hundreds of dollars.

Lauren Cohen, who teaches a third-grade inclusion class at a participating school, S.T.A.R. Academy at Public School 63 in the East Village, said having the New York Public Library's vast holdings at her fingertips offers her students more choices.

"In the past, it's been limited to, 'OK, we have a lot of books about weather, so you can read about weather!'" she said. "Now, it's letting kids feel like they have some power over what they read."

New York Public Library staffers already have created lists of books on specific topics that teachers can borrow all at once, including a third-grade reading list on Africa and a fourth- through seventh-grade list on American Colonial history. The books are delivered by UPS at no cost to the schools.

Public library officials said they would help create electronic catalogs for school libraries currently using card catalogs.

New York state law requires all middle and high schools to have licensed librarians. The city has roughly 1,700 public schools, 800 libraries and 365 licensed librarians.

New York Public Library spokeswoman Angela Montefinise said the library's portion of the pilot cost $1 million and was funded through philanthropic grants. Mr. Betheil said the city's work was performed by in-house staff at no additional cost.

City officials said the collaboration would help schools comply with new standards that require reading nonfiction books, which weren't commonly found in school libraries before.

At P.S. 63, the school shares a library—and a librarian—with the other school in its building, P.S. 363. The space, run by Cheryl Wolf, is stocked with puppets, graphic novels, children's cookbooks and iMacs, among other things, many of them purchased with grants.

She said the program would allow her to spend her limited budget on building the library's collection, rather than on curriculum texts that often change. "One year, I spent half the budget on Mesopotamia," she said.