Dorothy I. Height, 98, a founding matriarch of the American civil rights movement whose crusade for racial justice and gender equality spanned more than six decades, died early Tuesday morning of natural causes, a spokesperson for the National Council of Negro Women said.

Ms. Height was among the coalition of African American leaders who pushed civil rights to the center of the American political stage after World War II, and she was a key figure in the struggles for school desegregation, voting rights, employment opportunities and public accommodations in the 1950s and 1960s.

She died at 3:41 a.m. at Howard University Hospital, a spokesman there said.

Ms. Height was president of the National Council of Negro Women for 40 years, relinquishing the title in 1997. The 4 million-member advocacy group consists of 34 national and 250 community-based organizations. It was founded in 1935 by educator Mary McLeod Bethune, who was one of Ms. Height’s mentors.

As a civil rights activist, Ms. Height participated in protests in Harlem during the 1930s. In the 1940s, she lobbied first lady Eleanor Roosevelt on behalf of civil rights causes. And in the 1950s, she prodded President Dwight D. Eisenhower to move more aggressively on school desegregation issues. In 1994, Bill Clinton awarded her the Presidential Medal of Freedom, the nation’s highest civilian honor.

“She was a dynamic woman with a resilient spirit, who was a role model for women and men of all faiths, races and perspectives. For her, it wasn’t about the many years of her life, but what she did with them,” said former U.S. Secretary of Labor Alexis M. Herman, a close friend who has been running day-to-day operations at the National Council.

Herman called Ms. Heights “a national treasure who lived life abundantly. She will be greatly missed, not only by those of us who knew her well, but by the countless beneficiaries of her enduring legacy.”

In the turmoil of the civil rights struggles in the 1960s, Ms. Heights helped orchestrate strategy with movement leaders including the Rev. Martin Luther King Jr., Roy Wilkins, A. Philip Randolph, Whitney Young, James Farmer, Bayard Rustin and John Lewis, who later served as a Democratic member of the U.S. House of Representatives from Georgia.

Ms. Height was arguably the most influential woman at the top levels of civil rights leadership, but she never drew the major media attention that conferred celebrity and instant recognition on some of the other civil rights leaders of her time.

In August 1963, Ms. Height was on the platform with King when he delivered his “I have a dream” speech at the Lincoln Memorial. But she would say later that she was disappointed that no one advocating women’s rights spoke that day at the March on Washington for Jobs and Freedom. Less than a month later, at King’s request, she went to Birmingham, Ala., to minister to the families of four black girls who had died in a church bombing linked to the racial strife that had engulfed the city.

She was also energetic in her efforts to overcome gender bias, and much of that work predated the women’s rights movement. When President John F. Kennedy signed the Equal Pay Act in 1963, Ms. Height was among those invited to the White House to witness the ceremony. She returned to the White House in 1998 for a ceremony marking the 35th anniversary of that legislation to hear Clinton urge passage of additional laws aimed at equalizing pay for men and women.

As president of the National Council of Negro Women, Ms. Height was instrumental in organizing and sponsoring programs that emphasized self-help and self-reliance.

Those included nutrition, child care, housing and career counseling. In response to a public TV program, “The Vanishing Black Family,” Ms. Height helped create and organize the Black Family Reunion Celebration, which has been held on the Mall and in cities across the country annually since 1985. The gatherings are intended to honor the traditions, strength and history of African American families while seeking solutions to such social problems as teen pregnancy and drug abuse.

“The reunion is as important today as some of our marches were in the past,” Ms. Height said in 1992.

In 1995, Ms. Height was among the few women to speak at the Million Man March on the Mall, which was led by Louis Farrakhan, the chief minister of the Nation of Islam. “I am here because you are here,” she declared. Two years later, at 85, she sat at the podium all day, in the whipping wind and chill rain, at the Million Woman March in Philadelphia.

“If the times aren’t ripe, you have to ripen the times,” she liked to say. It was important, she said, to dress well. “I came up at a time when young women wore hats, and they wore gloves. Too many people in my generation fought for the right for us to be dressed up and not put down.”

She has also been quoted, “stop worrying about whose name gets in the paper and start doing something about rats, and day care and low wages. . . . We must try to take our task more seriously and ourselves more lightly.”