She was the "first lady of the civil rights movement." A deeply spiritual woman in ruby-red lipstick and brushed-back hair whose prayers and quiet grace anchored her Baptist preacher husband as he marched out to change the world.

Coretta Scott King, 78, who had heart problems and had suffered a major stroke last August, died during the night at Santa Monica Health Institute, a holistic health center in Rosarito Beach, Mexico, according to a spokesperson for the U.S. consulate in Tijuana.

Former Atlanta Mayor and U.N. Ambassador Andrew Young, who broke the news in a call to NBC's "Today" show yesterday morning, said Mrs. King's daughter, Bernice, had tried to wake her mother last night but found she had "quietly slipped away."

He hailed Mrs. King's strength and said it rivaled her husband's. "She was strong, if not stronger, than he was," Mr. Young, who worked alongside her husband in the civil rights campaigns of the 1960s, said in a news conference yesterday. "She lived a graceful and beautiful life and, in spite of all of the difficulties, she managed a graceful and beautiful passing."

Flags were lowered to half-staff on Georgia state buildings and at Atlanta's King Center, the organization she built to continue her husband's legacy of nonviolence and equality.

President Bush yesterday called Mrs. King "a remarkable and courageous woman."

Mrs. King, who picked cotton in rural Alabama as a child and later sat with presidents, was many things to many people, she told a standing-room-only crowd at California University of Pennsylvania three winters ago.

She told the audience she was "a complex, three-dimensional, flesh-and-blood human being with a rich storehouse of experiences, much like everyone else."

A prayerful woman, the former teacher, newspaper columnist and television commentator considered herself a human rights advocate and was a regal member of the civil rights elite.

Holder of a music degree from the New England Conservatory of Music, she became the stoic preacher's wife, the steel magnolia who prayed for her husband during the bus boycott in 1955; stood beside him when he won a Nobel Peace Prize in 1964; and marched beside him in Selma, Ala., in 1965.

In her sorrow and resolve, she's often been compared to Jacqueline Kennedy. Both manifested grace and eloquence after their husbands were slain.

For thousands of black women, she was also a symbol of quiet support of the struggle for justice during a tumultuous period in American history.

Mrs. King was a mother of four who gave up her own promising singing career to stay home. Her husband's dreams became her own.

"That was the feature of her generation," said Clarence B. Jones, a former speechwriter and counsel to Martin Luther King Jr. "It was more pronounced in the African-American Southern clergy tradition, but she became the bedrock of the household."

Coretta Scott was born April 27, 1927, in Marion, Ala. Her father ran a country store. In the 1930s, after the Great Depression hit, a young Coretta picked cotton to help her family.

She worked as a waitress to pay her way through Antioch College in Ohio, graduating in 1951 before attending the New England Conservatory of Music school in Boston.

In early 1952, a matchmaking friend asked if she would be interested in meeting a graduate of Morehouse College in Atlanta who was studying for his doctorate at Boston University. But the minute she heard that the young man was a minister, she lost interest, fearing that he would be too pious and narrow-minded for her taste.

But Martin Luther King Jr. called her anyway and made a strong play for her affections.

He struck her as short and unimpressive. But when he spoke, she said, "he grew in stature," revealing charisma, intelligence and moral passion.

She and the young doctoral student courted intensely over the next months. When she realized she was not the only object of his affections, she invited his other girlfriends to a surprise party for him -- and coolly eliminated them from contention.

"Coretta was all graciousness, thereby making it clear that she was in charge," Mr. Young wrote in his memoir, "An Easy Burden." "It was a nonviolent way to deal with one's opposition that Martin couldn't help but respect."

Later that summer Dr. King was offered the pastorship of Dexter Avenue Church in Montgomery, Ala. Although his wife was reluctant to give up the freedom and opportunities she had grown to enjoy in the North, she moved to Montgomery in September, after she earned her degree in voice and violin and Martin passed his exams.

It was at about the same time as the Rev. Bob Graetz, a white minister, came to town to lead a black Lutheran congregation, and just before the bus boycott that catapulted Dr. King into civil rights history.

Those were dark, violent times, said Mr. Graetz, who remembered that Mrs. King's "strong faith kept her going. She could never have survived being under constant threat without it. Even the children were under threat. She had to stand up. There were many days when Martin was close to the edge; she was an anchor for him."

But peril was ever-present. The Kings' house in Montgomery had been bombed in 1956 when Mrs. King was at home with baby Yolanda. No one was hurt, but angry blacks marched to the house with guns, ready to wreak havoc on the perpetrators.

"From that day on, I was fully prepared for my role as Martin's wife and partner in the struggle," she wrote in Good News magazine two years ago. "There would be many more days of difficulty and worry, there would be many more prayers. But the unwavering belief that we were doing God's work became a daily source of faith and courage that undergirded our freedom movement."

Then, in 1958, Dr. King was stabbed in the heart by a deranged black woman in Harlem; doctors said if he had sneezed, he would have died.

He also was jailed numerous times.

Plunged into the movement so soon after marrying, the Kings had little time to develop a normal family life. Dr. King traveled constantly: He was in jail or away on movement business when Martin III and Dexter were born in 1957 and 1961, respectively, and nearly missed the arrival of Bernice in 1963.

Although he often asked his wife to stand in for him at rallies when he had to be elsewhere, he usually wanted her to stay home and raise their family. Thus, she rarely joined her husband at marches, which bred resentment.

After her husband's assassination, she picked up his baton and steadily championed that his birthday be observed as a national holiday. It was first celebrated as such in 1986.

"She really saw the King holiday not as a way of honoring her husband, but as something to carry on his movement and not to let the ideas die," Mr. Graetz said.

In 1969 she began to mobilize support for the Martin Luther King Jr. Center for Nonviolent Change. She eventually raised $15 million to build the complex, which opened in 1982. Located within a 23-acre national historic park that includes his birth home, the center houses his tomb, a museum, a gift shop and archives. King ran the center as president.

She led the Atlanta center from its inception in 1969 until 1994, when she turned over the management to Dexter after a bruising battle with King Center board members who thought he was unqualified for the job. It is now headed by his brother, Martin Luther III.

Two daughters also survive her: Yolanda and Bernice.

The King Center has been attacked over the years for a lack of activism, and it has struggled financially. In the 1990s it began to run large deficits, and by 2005 it needed $11.6 million in repairs. The future of the center became the subject of an ugly family squabble, with Dexter and Yolanda pushing to sell the institution to the National Park Service despite the objections of Martin III and Bernice.

Several years earlier the King family had tried to block a National Park Service proposal to open its own exhibit on Rev. King, arguing that it would detract from the family-run center across the street. The Kings and the Park Service eventually resolved their differences, but the dispute tarnished the Kings' image.

Dorothy Height, a Rankin native and a former head of the National Council of Negro Women, said people everywhere are proud of Mrs. King. Ms. Height last saw her friend a year ago at a celebration of black women at the Oprah Winfrey mansion in California.

"What she did for us was institutionalize King's concepts of what it means to live in a nonviolent community. This way, we'll always have an opportunity to have his teaching and his preaching on how America can be her best, especially now when we seem to be losing ground in civil rights. Her work will remind us that we always need to work to build the beloved community."