American author and music critic. She was born Marcia Glick, daughter of Bernard Glick and opera singer Alma Gluck, later stepdaughter of violinist Efrem Zimbalist when Alma Gluck remarried.
Davenport traveled extensively with her parents and was educated intermittently at the Friends School in Philadelphia, Pennsylvania, and the Shipley School at Bryn Mawr. She began at Wellesley College but eloped to Pittsburgh in 1923 to marry Fred D. Clarke. Eventually she earned her B.A. at the University of Grenoble. Her first child was born in 1924, but in 1925 she divorced Clarke.
She took an advertising copywriting job to support herself and her daughter. In 1928 she began at the editorial staff of The New Yorker, where she worked until 1931. In 1929, she married Russell Davenport, who soon after became editor of Fortune. Davenport's second daughter was born in 1934. That same year she began as the music critic of Stage magazine.
Davenport had close ties through her mother and stepfather to the classical music world and particularly to the heady opera world of Europe and America in the first half of the 20th century. She was first celebrated as a writer for her first book, Mozart, the first published American biography of composer Wolfgang Amadeus Mozart. Her marriage to Russell Davenport ended in 1944.
She also wrote several popular novels, notably The Valley of Decision, a 1940s bestseller made into a successful movie with Greer Garson and Gregory Peck.