The Theatre Guild is a theatrical society founded in New York City in 1918 by Lawrence Langner, Philip Moeller, Helen Westley and Theresa Helburn. Langner's wife, Armina Marshall, then served as a co-director. It evolved out of the work of the Washington Square Players.

Philip Moeller was an American stage producer and director, playwright and screenwriter, born in New York where he helped found the short-lived Washington Square Players and then with Lawrence Langner and Helen Westley founded the Theatre Guild.