The show began as a radio series in 1944. David Nelson and Ricky Nelson were played by professional actors, because the Nelsons' sons were too young, but by 1949 the real David and Ricky were part of the show. In 1952 the show became a television series.
Ricky Nelson's launch as a rock star on this series is an interesting tale. He was already musically talented, having inherited his ability from his parents. As rock-n-roll was starting to grow and Ricky's interest in the music grew, he kept asking father Ozzie Nelson to let him play on the show. Initially, Ozzie resisted until he realized that it was an opportunity to take advantage of Ricky's growth as a "teen idol" and would thereby help the show's popularity. Ricky first sang a cover of Fats Domino's "I'm Walking" on the episode "Ricky the Drummer" and soon afterward more episodes were tailored around showcasing Ricky's talents. However, not everyone was pleased with his foray into Rock-n-Roll. Most parents in America were still concerned that rock would be a bad influence on their children and many wrote letters to Ozzie and Harriet Nelson protesting their allowing their son to take part in the music. The Nelsons dealt with the furor by injecting moments in the episodes in which Ozzie and/or Harriet would offer a sound and practical reasoning for supporting their son's music. With that, the furor died down and Ricky went on to become a major rocker with hits like "It's Late", "Traveling Man" and "Hello, Mary Lou".
Actors Lyle Talbot and Mary Jane Croft were well known for playing married couple Joe and Clara Randolph in the mid-to-later years of the series, but the pair we're originally cast as a different set of marrieds, Harvey and Marion Burnette for one episode early on. Apparently the chemistry was good enough to make them more or less a fixture in the show.