De Lancie has been a member of the American Shakespeare Festival, the Seattle Repertory Company, South Coast Repertory, the Mark Taper Forum, and the Old Globe (where he performed Arthur Miller's Resurrection Blues).

He has performed and directed for Los Angeles Theater Works, the producing arm of KCRW-FM and National Public Radio, where the series The Play's the Thing originates.

De Lancie appeared in Star Trek: The Music, a touring company, with Robert Picardo.
De Lancie and Picardo narrate around the orchestral performance, explaining the history of the music in Star Trek.
He performed Pierre Curie in Alan Alda's play, Radiance: The Passion of Marie Curie in 2001 at the Geffen Theater in Los Angeles.
De Lancie has been a member of the American Shakespeare Festival, the Seattle Repertory Company, South Coast Repertory, the Mark Taper Forum, and the Old Globe (where he performed Arthur Miller's Resurrection Blues).
He has performed and directed for Los Angeles Theater Works, the producing arm of KCRW-FM and National Public Radio, where the series The Play's the Thing originates.
De Lancie appeared in Star Trek: The Music, a touring company, with Robert Picardo. De Lancie and Picardo narrate around the orchestral performance, explaining the history of the music in Star Trek. He performed Pierre Curie in Alan Alda's play, Radiance: The Passion of Marie Curie in 2001 at the Geffen Theater in Los Angeles.
John de Lancie