Published by Crown in 1990, Davis's second book, Don't Know Much About History, spent 35 consecutive weeks on The New York Times bestseller list and sold nearly 1.5 million copies. This unexpected success launched the Don't Know Much About... series. The standardized format is a chronological coverage of a subject with each chapter divided into boldface subheads of questions, such as, "Did Pocahontas really save John Smith's life?" Davis then answers the questions with basic facts delivered in short easy-to-read essays which have a straight-forward approach, but sometimes grab the reader's attention by beginning with light humor and anachronistic comparisons, for example: "Even the astronauts who flew to the moon had a pretty good idea of what to expect; Columbus was sailing, as Star Trek puts it, 'where no man has gone before'." Quotes from historical figures often follow the essays.

The titles were initially inspired by Sam Cooke's song "Wonderful World," with the lyrics, "Don't know much about history" or "geography," etc. Because Davis makes history palatable to bored students, the series has generally received favorable reviews, and praise from teachers and librarians. One mixed review criticized Davis for "treat[ing] his subject matter as a vehicle for his own editorials".

Davis's current publisher is HarperCollins. In his most recent book, America's Hidden History: Untold Tales of the First Pilgrims, Fighting Women, and Forgotten Founders Who Shaped a Nation (2008), he drops the earlier Q&A format for a more traditional style of writing which explores little-known aspects of American history. Spanning a period from the Spanish arrival in the Americas to George Washington's 1789 inauguration, these narratives have a more serious tone than the earlier books, are more expansive, and focus not only on well-known names but also on forgotten figures such as Hannah Duston.