Aileen Hernandez, left, with women’s rights activist Gloria Steinem in 2013. (Richard Shotwell/Invision/Associated Press)

Aileen Hernandez, a founding member and former president of the National Organization for Women who spent decades on the vanguard of the sometimes competing feminist and civil rights movements, died Feb. 13 at a memory-care facility in Tustin, Calif. She was 90.

The cause was complications from dementia, said a niece, Annie Clarke.

The daughter of Jamaican immigrants, Ms. Hernandez grew up as the only daughter in the only black family in their Brooklyn neighborhood. She credited her mother with inspiring her political activism, in part by taking her along to confront a man who had agitated to remove them from the block.

“I learned something that day, although I was very little at that stage,” Ms. Hernandez said in an interview for the Makers, an online archive of interviews with prominent women.

Her commitment to working for civil rights was galvanized when she arrived in Washington to attend Howard University. At the train station, she was directed to hail a “black taxi cab.” As a New Yorker not yet fully acquainted with the indignities of segregation, she assumed “black” to be the color of the cab. It turned out, she ruefully recalled in an interview with the KQED public television station, to indicate the color of the driver’s skin.

After graduating, Ms. Hernandez rose through the ranks of the International Ladies’ Garment Workers’ Union in California, working to secure parity in compensation.

In 1965, President Lyndon B. Johnson named her the first and, at that time, only woman on the Equal Employment Opportunity Commission. The federal agency had been established that year to ensure compliance with the federal ban on employment discrimination based on race, color, religion, sex and national origin.

Ms. Hernandez pushed the agency to address education and housing concerns, which she regarded as inextricably linked to employment opportunity. She left the post after less than two years, seeking faster changes in women’s rights.

“We have no right to determine that we will not be as forthright in attacking one kind of discrimination as we are in attacking another kind,” she wrote in a 1966 memo. “I confess that I am basically oriented to eliminating the centuries-old discrimination against Negroes, but I cannot close my eyes to the obvious inequities of treatment of other groups in our society.”

After leaving the EEOC, she became executive vice president of NOW. In 1970, she succeeded Betty Friedan, the founding president, at the helm. In that role, Ms. Hernandez sought to improve what she described as the group’s “embarrassingly elitist and middle-class” image

“I’m much more interested in the problems of the mass woman than the professional,” she told Newsday in 1970, according to the reference guide Current Biography, “the women who are trapped in menial jobs, the woman who aspires to become a nurse but never a doctor, an elementary school-teacher but never a professor. The low-income woman isn’t going to run to join NOW, but she’s going to relate to our program because she has known for a long time the problems of combining a family with a job.”

According to NOW, Ms. Hernandez oversaw the Women’s Strike for Equality in 1970, marking the 50th anniversary of women’s suffrage in the United States; helped found the National Women’s Political Caucus; and led advocacy work against sex discrimination in the workplace. She handed off the presidency to Wilma Scott Heide in 1971 and later ran an employment consulting firm.

Aileen Blanche Clarke was born in Brooklyn on May 23, 1926. Her father was employed at an art-supply store, and her mother was a garment worker. She recalled that she and her brothers all were expected to contribute to household duties and that all three children learned to cook and sew.

After excelling in school, she was admitted to Howard, where she joined a collegiate chapter of the NAACP and where she received a bachelor’s degree in political science and sociology in 1947. She received a master’s degree in government from California State University at Los Angeles in 1961.

Her first public post was with the California state government’s division of Fair Employment Practices, where she served as assistant chief before joining EEOC.

Besides her engagement with NOW, Ms. Hernandez was involved with organizations including Black Women Organized for Political Action.

Her marriage to Alfonso Hernandez, a garment cutter, ended in divorce, and she had no immediate survivors.

Although Ms. Hernandez spoke admiringly of the advances during her lifetime in women’s and civil rights, she saw room for more progress to be made.

“We have not made it. We have not made it by any way,” she said in 2013. “So we have a lot of work to do, and we need the young people to know the history.”