He also played Digby Dropout's sidekick "Dunce" in The Man from Alphabet, a detective show which appeared in Sesame Street's pilots but was not used in the actual series due to poor testing results.

One year later in 1973 Thurman did the voice of Christopher Clumsy for a Cliff Roberts-produced cartoon about shapes as well as Jake the Snake in 1988 (also for Sesame Street).

In 1982, Thurman teamed up with Paul Fierlinger to create, write, and voice Teeny Little Super Guy for Sesame Street.

Thurman subsequently worked on most of CTW's other series, as a staff writer and cartoon voiceover on The Electric Company and 3-2-1 Contact, Fat Albert and the Cosby Kids, and as head writer/senior producer for Square One TV; on the later series, he provided the voice of Mr. Glitch and the off-screen announcer for Mathman, scripted the Mathnet segments, and Dirk Niblick of the Math Brigade.

In recent years Jim continued to write, do voice work, and also wrote a weekly column for his local paper, the Berkshire Record.