Headlines in the satirical weekly newspaper The Onion tend to function both as punch line and setup, in that order. They are the heart of the paper, and not only the first thing anybody reads, but also, unlike headlines in real newspapers all over the world, the first things to be written. The staff devotes the first two days of every week to composing headlines, then assigns the articles that will run beneath them and provide a body of supporting jokes.

It’s immediately apparent just flipping through “Our Front Pages: 21 Years of Greatness, Virtue, and Moral Rectitude From America’s Finest News Source,” the new, platter-size hardcover collection, appropriately enough, of front pages from The Onion, that the art of the fake headline has evolved. Early-era front-page type in the paper, founded in 1988 in Madison, Wis., had the clownish tone of a college-town humor rag: “Depressed? Try Liposuction on that Pesky Head.”

“You can see it took a little while before the paper was keyed in on the USA Today model,” said Joe Randazzo, the current editor of The Onion. (From 1998: “Inside: America Rates The Skin Colors. See Society, page 1D.”)

The paper relocated to New York in 2001, and that year, prompted partly by 9/11, the headlines took on what Mr. Randazzo called “more of a New York Times-Washington Post kind of tone  sober, important.” “We wait to chime in on a news event until after the news has chimed in,” he said. “The Onion’s charter is to be the last word, the newspaper of record. That’s a total conceit, of course, but we take it seriously, in the sense that we want to be the joke that’s making a joke about all the other jokes.”