1, 2, 3 Go! is a 1961-1962 American filmed children's television series hosted by Jack Lescoulie with Richard Thomas.[1] The show also featured Richard Morse, only for the first episode as The Courier, and Joseph Warren, who portrayed Thomas Jefferson in the first episode.

The half-hour educational series was telecast on NBC, opening with this theme song:

Wonder what it'll be today?
What excitement is on its way?
You can find out just by saying...
1, 2, 3 Go!
Each episode had a theme and was narrated by Thomas. The episodes show what it's like to be in various occupations, including fire fighter, astronaut and trapeze artist.[2]

The show established that adults and children were on an equal footing, sometimes with the child in a superior position. For example, in a show with a theme of cinematic special effects, Lescoulie is struck in the neck by an arrow. Although Richard explains it is only a special effect, Lescoulie remains concerned. In the narration, Richard observes, "Jack was getting worried about the arrow, but I told him to stop crying."