Slate will introduce a monthly book review on Friday, the latest expansion of literary criticism online as stand-alone book review sections in newspapers have dwindled.

The section will nearly triple the number of book-related articles that Slate publishes, covering fiction, nonfiction and the occasional children’s book.

Dan Kois, a senior editor in the culture department, will oversee the book review, which will use a mix of staff writers and freelancers to produce author interviews, essays and multimedia pieces, as well as reviews.

Mr. Kois said that even as he watched many newspapers drop their book sections in recent years, “it didn’t seem to me that there was less of an appetite for good writing about books.”

“Maybe the mode of doing it in print wasn’t appealing to editors or bean-counters,” said Mr. Kois, a former editor at New York magazine who helped develop its popular Vulture entertainment section. “So to my mind, I wanted to bring to Slate this idea of a concentrated, intense focus on books over the course of one weekend, where books essentially take the site over.”

Called the Slate Book Review, it will be published on the first Saturday of each month. The first section will have 13 articles.

For years, authors and publishers have been lamenting the disappearance of book review sections, which were once a mainstay of newspapers everywhere and a sure way to lift book sales.

The stand-alone book review section in print newspapers has become nearly extinct, a casualty of decreased advertising revenue and newspaper industry malaise. In 2009, The Washington Post announced that it would close Book World, its Sunday book review section, moving the reviews to other sections of the paper. The Los Angeles Times closed its stand-alone Sunday section in 2007.

A few exceptions remain, including The New York Times and The San Francisco Chronicle.

Other newspapers have experimented with a pay model: this week, The Chicago Tribune introduced Printers Row, a subscription section in both print and online that is focused on books, author interviews and reviews.

Meanwhile, the number of books published every year has exploded, leaving a wider gap between the titles published and those that are reviewed.

Magazines and journals like The New Republic, The Nation and The New York Review of Books are a few of the publications that have stubbornly resisted scaling back the space devoted to book reviews.

And a lot of literary criticism has moved online.

The New Republic has created The Book, which reviews a new book almost every day of the week, publishes literary pieces from the magazine’s archive and aggregates other literary reviews. The Millions, a well-regarded online magazine with coverage of books and the arts, was created in 2003. The Los Angeles Review of Books, a new literary Web site, was founded last year.

Eric Banks, the president of the National Book Critics Circle, said that while online book reviews have helped make up for the loss of print reviews, they have not been able to fill the void completely.

“Those online sites have done a terrific job in providing book review coverage,” he said. “But it’s a lot of ground to make up. You still lack the celebratory moment when a book gets reviewed in a pullout section of a newspaper.”