Set in the fictional town of Oakdale, Illinois, the show debuted on April 2, 1956, at 1:30 pm EST. Prior to that date, all serials had been 15 minutes in length. As the World Turns and The Edge of Night, which premiered on the same day at 4:30 pm EST, were the first two to be 30 minutes in length from their premiere. At first, viewers were indifferent to the new half-hour serial, but ratings picked up in its second year, eventually reaching the top spot in the daytime Nielsen ratings by fall 1958. In 1959, the show started a streak of weekly ratings wins that was not interrupted for over 12 years. The show switched to color on August 21, 1967, and expanded from a half-hour in length to one hour starting on December 1, 1975, when The Edge of Night moved to ABC. In the year-to-date ratings, As the World Turns was the most-watched daytime drama from 1958 until 1978, with ten million viewers tuning in each day. At its height, core actors such as Helen Wagner, Don MacLaughlin, Don Hastings, and Eileen Fulton became nationally known. Three of these actors – Wagner, Hastings, and Fulton – are also the three longest serving actors in the history of American soap operas.
The show passed its 10,000th episode on May 12, 1995, and celebrated its 50th anniversary on April 2, 2006. On September 18, 2009, As the World Turns became the last remaining Procter & Gamble-produced soap opera for CBS after Guiding Light aired its final episode on the network.
On December 8, 2009, CBS announced that it was canceling As the World Turns due to low ratings. The show taped its final Procter & Gamble scenes for CBS on June 23, 2010, and with a dramatic storyline finale, its final episode on the network aired on September 17, 2010. On October 18, 2010, CBS replaced As the World Turns with a newly debuted talk show The Talk.
As the World Turns was the creation of Irna Phillips, who beginning in the 1930s, had been one of the foremost creators and writers of radio soap operas. As a writer, Phillips favored character development and psychological realism over melodrama, and her previous creations (which included Guiding Light) were especially notable for placing professionals – doctors, lawyers, and clergy – at the center of their storylines. Phillips wrote: "As the world turns, we know the bleakness of winter, the promise of spring, the fullness of summer, and the harvest of autumn—the cycle of life is complete."
And so it was with As the World Turns, with its slow-moving psychological character studies of families headed by legal and medical professionals. The personal and professional lives of doctors and lawyers remained central to As the World Turns throughout its run, and eventually became standard fare on many soap operas. Whereas the 15-minute radio soaps often focused on one central, heroic character (for example, Dr. Jim Brent in Phillips' Road of Life), the expanded 30-minute format of As the World Turns enabled Phillips to introduce a handful of professionals within the framework of a family saga.