This book provides the first comprehensive introduction to Simone de Beauvoir's philosophical thought. Beauvoir has long been recognized as the twentieth century's leading feminist writer, but the full extent of her significance as a philosopher is just coming into focus. This study examines the history of Beauvoir's development into one of the most original and influential thinkers of her era. The Fullbrooks begin with an account of Beauvoir's formation as a philosopher. They then explore her early writing on philosophical method and the ways this shaped her fiction. The book traces the development of Beauvoir's central theories of embodied consciousness and intersubjectivity, and examines her concepts of the "individual" and the "social other". An analysis of Beauvoir's ethics of liberation leads to philosophical readings of her great works of applied ethics, The Second Sex and Old Age. Finally, Beauvoir's contribution to continuing debates about consciousness, the body, the self and the other is reassessed. The publication of this introduction to Beauvoir's philosophy is an important contribution to the current renaissance of Beauvoir studies. Clear, accessible and lively, this book is essential reading not only for students of Beauvoir but for anyone interested in the submerged record of women's impact on philosophy.