Dallas debuted on April 2, 1978, as a five-part miniseries on CBS. Although the miniseries was created as the series' pilot, by the time it was aired, neither the producers nor the network were hopeful that it would continue beyond these five episodes and initially had no plans for expansion. It was shown in a late Sunday night time-slot, known for low ratings. However, the miniseries proved popular enough to be turned into a regular series and broadcast for 13 full seasons from September 23, 1978, to May 3, 1991. The five pilot episodes, originally considered a miniseries, are now referred to as season 1, making fourteen seasons in total.

The show is known for its portrayal of wealth, sex, intrigue, conflict and power struggles. Throughout the series, the main premise is the longtime rivalry between the Ewing and Barnes families, which came to head when the Barnes daughter Pamela (Victoria Principal) eloped with youngest Ewing son Bobby (Patrick Duffy), in the first episode. The series is largely set in Dallas, Texas, and fictional Braddock County, where the Southfork Ranch is located.

The backstory was that, in the 1930s, wildcatter John Ross "Jock" Ewing (Jim Davis) had allegedly cheated his one-time partner, Willard "Digger" Barnes (David Wayne/Keenan Wynn), out of his share of their company Ewing Oil, and married Digger's only love, Eleanor "Miss Ellie" Southworth (Barbara Bel Geddes/Donna Reed). In contrast to Jock, Miss Ellie came from a long line of ranchers with great love for the land and the cattle. Following their marriage, the Southworth family ranch, Southfork, became the Ewings' home, where Jock and Miss Ellie raised three sons: J.R. (Larry Hagman), Gary (David Ackroyd/Ted Shackelford) and Bobby.

J.R., unscrupulous and unhappily married to former Miss Texas beauty queen Sue Ellen Shepard (Linda Gray), was frequently at odds with Bobby, who had the morals and integrity that J.R. lacked. Middle son Gary was Miss Ellie's favorite as he displayed Southworth traits; however, Gary had been in conflict with both Jock and J.R. since childhood and was dismissed as a weak link. At 17, Gary secretly met and married 15-year-old waitress Valene Clements (Joan Van Ark), producing the first Ewing grandchild - petite and saucy Lucy (Charlene Tilton) - before returning to Southfork with the intention of settling down. Although Jock warmed to Valene and supported Gary's fledgling family, J.R. pressured Gary into alcoholism by landing him with bad business deals that caused him to flee Southfork. With Gary gone, J.R. persecuted Valene until she left the ranch and the state, leaving Lucy to be raised by her grandparents.