The Chicago Tribune is a major daily newspaper based in Chicago, Illinois, and the flagship publication of the Tribune Company. Formerly self-styled as the "Worlds Greatest Newspaper" (for which WGN radio (WGN (AM)) and television (WGN-TV) is named), it remains the most read daily newspaper of the Chicago metropolitan area and the Great Lakes region (Great Lakes region (North America)) and is currently the eighth largest newspaper in America by circulation (and the second largest under Tribunes ownership behind Los Angeles Times). Traditionally published as a broadsheet, on January 13, 2009, the Tribune announced it would continue publishing as a broadsheet for home delivery, but would publish in tabloid format for newsstand, news box, and commuter station sales.

On April 2, 2007, the Tribune Company announced a buy-out plan led by Chicago real estate magnate Sam Zell worth $8.2 billion, associated with a stock buyback at $34 per share, and an Employee Stock Ownership Plan. The deal closed on December 20, 2007, with Zell as the companys new chairman. As part of the deal, the company sold the Chicago Cubs and its properties, including Wrigley Field and a stake in Comcast SportsNet Chicago, to the family of J. Joseph Ricketts. Less than a year after the deal closed, the Tribune Company filed for Chapter 11 bankruptcy protection on December 8, 2008.