Mr. I. Magination was one of the earliest television shows for children. It ran live as a half-hour weekly show on CBS from 1949 to 1952 and was broadcast from Manhattan.

The host, Mr. I. Magination, dressed as a train engineer, gathered a group of children each week. The same child actors appeared on a rotating basis. Two would be selected to ask about a career, occupation, activity, and such. Tripp would then play a "magic" slide flute, he and the children would board a train and travel to Imagination Land, where they would meet a professional from each of the two areas for that week's show.

Guests were as diverse as Damu, a lion tamer from Ringling Brothers Circus, and test pilot Scott Crossfield. His wife, Ruth Enders Tripp, also acted in the show. The show was also a pioneer in using simple, early special effects, such as making it appear as if the opening train ride went through a tunnel to enter Imagination Land, emerging from the smoke from its engine.

Yul Brynner served as the director of the show at times, but did not appear as a performer. The show also featured performances by Walter Matthau, Richard Boone, Joe Silver, Ted Tiller, and Simon Oakland.