Although Marguerite Yourcenar (1903-1987) lived in the US for almost fifty years and became an American citizen in 1947, few people understand the influence it had on her work. Biographers, critics and scholars have wrongly imagined she was untouched by her life in America – that she remained French to the core, linguistically isolated, culturally “pure”, that she never took an interest in the country where she lived for half her life. This penetrating new study of Yourcenar in America demonstrates the opposite. It shows how the natural setting of her adopted homeland, as well as its politics, culture and environmentalist movement, along with America’s emergence as a super power and the American way of life affected what Marguerite Yourcenar wrote and how she wrote it. Drawing on Yourcenar’s works as well as on her voluminous archives at Harvard’s Houghton Library, this innovative analysis sheds new light on Yourcenar’s American inspirations and influences. An interview of Marguerite Yourcenar by the American journalist TD Allman, a letter from Marguerite Yourcenar written in English, an amazing photograph from Life magazine, and entries from her companion Grace Frick’s diaries are among the previously unpublished documents which bring to life the American side of Yourcenar’s literature. This investigative study also reveals that Marguerite Yourcenar, far being limited to French, had an outstanding mastery of the English language. It shows how she became an authentic heir of a long and vivid American tradition: protest literature.