Born Betty Naomi Goldstein in 1921 in Peoria, Ill., Friedan graduated from Smith College in 1942 and was a graduate student at the University of California at Berkeley. She married Carl Friedan in 1947.
She was a journalist but when she had her second child she was denied maternity leave.
As a freelance writer, while raising three children, Friedan wrote about her 15-year college reunion in 1957 and found many classmates, who were also housewives, were dissatisfied. Further research led to the best-seller "The Feminine Mystique," which sold over 3 million copies.
In 1966, Betty Friedan and 27 other women and men founded NOW. She served as president from 1966-70. She was also among the founders of the National Abortion Rights Action League and one of leaders who formed the National Women's Political Caucus.
She also wrote "It Changed My Life: Writings on the Women's Movement"; "The Second Stage"; and "The Fountain of Age."
She divorced in 1969 and is survived by her three children and nine grandchildren, the New York Times said.