Simone de Beauvoir played a significant role in establishing the French feminist movement with her influential works, particularly "The Second Sex." Published in 1949, the book critiques the historical treatment of women and explores the concept of gender equality. De Beauvoir's ideas challenged traditional views of femininity and advocated for women's liberation and independence. Her contributions laid the intellectual groundwork for the feminist movement in France and inspired subsequent generations of activists seeking social change and gender justice.