Eleanor Ruggles was born into a prominent literary family. Her maternal great-grandfather and great-grand-uncle wrote the McGuffey Readers, the popular 19th-century schoolbooks. Her father was a judge on the Nantucket circuit and she grew up in tony Beacon Hill, Boston. In 1938, she graduated with a degree in English and theater arts from Vassar, where she studied with John Houseman and acted in college plays, as well as writing for college publications. Hoping for an acting career, she went to London to study drama with Elsie Fogarty. Back in the USA, she became a director of the Duchess County Players in New York. She also worked with the Group 20 Theatre and the Theatre Guild of New York City, where she befriended a group of actors and playwrights including Clifford Odets and Orson Wells. She married Robert Semmes O'Leary, a faculty assistant at Harvard University and later an editor of the New England Journal of Medicine, and went to live with him in Cambridge. Under her maiden name, she wrote book reviews for The Boston Globe, mainly on biographies and autobiographies, and then began producing her own books. Her critically acclaimed biography of actor Edwin Booth, The Prince of Players (1953) was quickly adapted into a Hollywood film. Her other books included Gerard Manley Hopkins: A Life (1944), and The West Going Heart (1959).