Thirty Day Princess is a 1934 pre-Code comedy film directed by Marion Gering and starring Sylvia Sidney, Cary Grant and Edward Arnold. The film was based on a story of the same name by Clarence Budington Kelland, adapted by Sam Hellman and Edwin Justus Mayer, and written by Preston Sturges and Frank Partos.

Marion Gering was a Russian-born American stage producer and director. He moved to the United States in 1923 as an artist. He became involved in the theatrical community in Chicago, founding the Chicago Play Producing Company.