The Comedy Central book club

One more thing about which one is not surprised.

About a year ago, publicists began noticing that Mr. Stewart was interviewing serious authors, said Lissa Warren, the senior director of publicity for Da Capo Press. “It was almost an ‘oh my God’ moment,” she said. “There aren’t that many television shows that will have on serious authors. And when they do have one, it’s almost startling.”

Part of the surprise, publishers said, is that the Comedy Central audience is more serious than its reputation allows. The public may still think of the “Daily Show” and “Colbert Report” audience as a group of sardonic slackers, Gen-Y college students who prefer YouTube to print. But publishers say it’s a much more diverse demographic — and more important, a book-buying audience.

“It’s the television equivalent of NPR,” Ms. Levin, of Free Press, said. “You have a very savvy, interested audience who are book buyers, people who do go into bookstores, people who are actually interested in books.”

According to Nielsen Media Research, the nightly audience for “The Daily Show” averages about 1.6 million, while “The Colbert Report” attracts an average of 1.2 million. (“The 1/2 Hour News Hour” on Fox, the conservative answer to the Comedy Central shows, had its premiere with 1.5 million viewers last Sunday but does not plan to do author interviews, a Fox spokeswoman said.)

Reading comprehension would not match up well with Fox News' demographics.