Simone de Beauvoir, still a teen, began a diary while a philosophy student at the Sorbonne. Written in 1926-27--before Beauvoir met Jean-Paul Sartre--the diaries reveal previously unknown details about her life and times and offer critical insights into her early intellectual interests, philosophy, and literary works. Presented for the first time in translation, this fully annotated first volume of the Diary includes essays from Barbara Klaw and Margaret A. Simons that address its philosophical, historical, and literary significance. It remains an invaluable resource for tracing the development of Beauvoir's independent thinking and her influence on philosophy, feminism, and the world.