Not only did Ruth work in film but also in theater, performing in a number of theater productions on and off Broadway.

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In 1957, Warrick was cast in her first Broadway show, Miss Lonelyhearts, as Mary Spain. Warrick received more than 37 telegrams from family, friends, and fans wishing her well on opening night and their hopes for a long run.

 

In 1973, Warrick was cast alongside Debbie Reynolds in the Broadway show Irene, as Emmeline Marshall.