Born in London, England, on October 16, 1908, Olivia Ensor Coolidge grew up in Buckinghamshire, where she was educated at the Wycombe Abbey School. She later attended Somerville College, Oxford, and received bachelor's and master's degrees. She has taught the classics and English in Great Britain, Continental Europe, and America, and has served on the board of trustees of Mills College of Education in New York. A naturalized U.S. citizen, she is married and has four children.
Coolidge began writing as a child. After World War II, she started publishing books for young readers. Most of her work addresses political and historical themes or retells classical mythology. She has chronicled the lives of Abraham Lincoln, Tom Paine, Winston Churchill, and Gandhi. She has also written about modern political developments, including the rise of communism in Russia and the early years of the American women's rights movement. Coolidge's only fictional work, Come by Here, recounts the difficulties of a young orphan black girl growing up in early twentieth-century Baltimore.