Born in Saginaw, Michigan, Nelson was the daughter of vaudeville actress Eva Mudge. She attended Immaculate Heart High School in Los Angeles and went on to study at the American Laboratory Theatre in New York City during the early 1920s. Nelson made her New York City stage debut as a member of the theatre collective Group Theatre throughout its run from 1931 to 1941, receiving praise for the role of the chief striker’s wife in Clifford Odets’ play Waiting for Lefty. After Group Theatre ended in 1941, Nelson relocated to Hollywood. Throughout the 1940s, she made a number of movies for 20th Century Fox and other Hollywood studios. One of these was A Tree Grows in Brooklyn (1945), directed by fellow Group Theatre member Elia Kazan. She also appeared in Kazan’s film The Sea of Grass in 1947. As her career began to take off, she was compelled to put things on hold when her husband, the director John Cromwell, a leading Roosevelt Democrat in the film industry, was falsely accused of Communism by actor Adolphe Menjou in front of the House UnAmerican Activities Committee hearings on Hollywood in 1951 and his career went on to be blacklisted. While offered a New York stage role as a wife in what turned out to be Death of a Salesman, Nelson turned down most acting offers at this time to stay in Los Angeles and support Cromwell. Nelson had not make a Hollywood film for nearly 30 years before appearing with her husband in 1977’s 3 Women, directed by Robert Altman, and The Late Show, a film Robert Benton wrote and directed that Altman produced. She and Cromwell played husband and wife as the aged patriarchal grandparents in the ensemble cast of Altman’s black comedy the following year, A Wedding. Her final feature-film role was in 1990’s Awakenings, as the mother of a hospital patient played by Robert DeNiro. Nelson was married twice. She wed actor William Challee in 1931. The marriage later dissolved and Nelson married actor/director John Cromwell in 1946. The marriage lasted 33 years, when Cromwell died in 1979 of pulmonary embolism. She was the stepmother of actor James Cromwell. Nelson died on September 12, 1992 at her home in New York City from cancer complicated by a stroke and pneumonia.