Betty Friedan authored the landmark book "The Feminine Mystique," which significantly advanced the women's liberation movement in the 1960s. Her groundbreaking work highlighted the dissatisfaction of many American women, challenging the traditional roles assigned to them. Friedan's writing prompted a reevaluation of women's rights, emphasizing the need for economic and social equality. Her book sparked widespread discussion and activism that led to greater awareness of gender issues, laying the groundwork for future advocacy efforts.