Eugenia (Genii) Guinier died on August 9. She was 91.

Genii Paprin Guinier was a woman before her time. During World War II, Genii Paprin, a Hunter College graduate who had majored in French, with a master’s degree from the University of Michigan, volunteered for the Red Cross and was shipped to Hawaii.

In Hawaii, she, a child of Jewish immigrants, broke off her engagement to a nice Jewish doctor and married a black man, Ewart Guinier, who was serving as a warrant officer in the then-segregated U.S. Army. He was a union organizer and labor leader, a member of the Harvard Class of 1933 who dropped out when he could not pay his tuition (Harvard had early on denied him a scholarship on the grounds that he had failed to submit his “photograph” with his application; he also was not permitted to live in the dormitories, which were segregated at the time).

They met at a Labor Canteen in Honolulu in August 1945. They married two months later in October. For the rest of Genii’s life, Hawaii remained the most romantic, the most optimistic, the most beautiful place in the world to her. Even as she descended into dementia in her later years, aloha nui loa was the way she said goodbye.

She married a black man when such a relationship was illegal in many states. At the same time, she married a “race man.” Returning to New York city, Ewart Guinier ran for Manhattan borough president in 1949, the first black to compete for that job, winning almost 100,000 votes, an impressive showing for a third-party candidate. He then served as campaign manager for W.E.B. DuBois’s quixotic run for U.S. Senate in 1950. Later in life he became the first person to lead the Department of Afro-American Studies at Harvard, where he developed the template for the W.E.B. DuBois Institute. When he died, Genii contributed his papers to the Schomburg Library in Harlem, because she did not want the papers buried in a place where you needed the right credentials to see them. During an earlier trip to Africa, Genii and Ewart donated some of his books to the University of Dakar, Senegal to begin the Ewart Guinier collection there.

Over time Genii also became a “race woman.” She lived in the black community, raised three black daughters, became close with her husband’s five sisters and a mentor, friend and confidante of her niece Sheila Williams. Following two of Ewart’s sisters, Ewart and Genii moved to Hollis, Queens in 1956, to integrate a neighborhood of proud, working class Irish and Italian families. The Guiniers were the first family of color on the block. Within six years Hollis changed. It was renamed by the post office as St. Albans, and Genii, it seemed, was the only white person still living in the neighborhood.

But the Guiniers had changed more than zip codes, according to Genii’s daughter, Lani. “No longer were we interracial. We were now black.”

“At some point,” New York University Prof. Derrick Bell explained in an e-mail message, “Genii crossed the line.” By that, Professor Bell meant that she took up the cause of racial justice as her own. She boycotted Woolworths and attended the 1963 March on Washington for Jobs and Freedom.

She became a fierce supporter of civil rights. Genii’s friend Vera Shorter said, “Any group functioning for the betterment of black people, Genii was there ... She was extremely conscious of the ills of the time against black people, and she did what she could to change this.”

In the 1960s, along with her buddy Dora Grain (who died last year after living more than 30 years on the Vineyard), Genii Guinier helped jump-start a chapter of the Association for the Study of African American Life and History in St. Albans, N.Y., where they both were raising their families.

Genii “crossed the line” not only because of the causes she championed but also because of the friends she held dear. For example, Professor Bell’s first wife, Jewel, died of cancer in 1990, but by that time she and Genii, according to Bell, had become “sisters” intellectually, emotionally, spiritually.

In 1965 Genii discovered Martha’s Vineyard. Like Hawaii, it was an Island. It was a place to enjoy the majestic seascapes and sleep soundly to the music of the sea breezes. Like Hawaii, it was more diverse than the mainland. But unlike Hawaii, where black people are still scarce, Oak Bluffs offered an energetic and self-confident black community with people of varying interests from tennis players, swimmers, artists, music lovers to intellectual soulmates. The Vineyard, like Hawaii, became a mecca for Genii’s imagination — drawing her to its karma every year from 1965 to 2007. She bought a house in East Chop in 1972. Once again the Guiniers were the only black family on the block. “In fact my mom had to buy the house in her name only to conceal the fact that a black family was about to move in,” her daughter recalled.

Genii Guinier by day was a speech therapist and a high school English teacher, in high-performing suburban public high schools as well as technical high schools like Alexander Hamilton in Brooklyn, N.Y. or Shawsheen Technical High School in Massachusetts. There she met her dear friend Evelyn Tyner, who has been coming to the Vineyard with her own family since the 1940s. Genii’s special gift, Evelyn Tyner’s daughter Leona Martin says, was “convincing people to do things on behalf of others. She got you involved because you knew she was not just doing it for herself. [She had] the courage to teach people.”

Genii was an instigator with a curiosity about her and high expectations of the people around her. “She had opinions but she was also interested in your opinion,” Ms. Martin said. Genii got people to do things. Her mother, Evelyn Tyner, agreed. “Genii was very persuasive. Genii convinced me to join an intergenerational dance group, the Back Porch Dance Company, when we were both in our late 70s. The only thing she was unable to convince me to do was play tennis.”

Almost 30 years ago, Genii cofounded a book club on Martha’s Vineyard, Women Reaching. The book club focused on black writers and aimed at bringing greater consciousness of their work to the reading public. Vera Shorter, one of the club’s early participants, says the club was a source of intellectual discovery and camaraderie. Vera said, “[Genii wanted] the reading public to know about black writers and to read them.” Dorothy Burnham, another close friend, Oak Bluffs resident, and book club member, said Genii knew many of the authors who came and spoke to the book club. She entertained author John Killens and his wife, and according to Dorothy was an avid dinner party host for visitors and Islanders. But food was not the focus; it was the conversation after dinner that mattered. Leona Martin: “Genii was very much an intellectual, because of the things she questioned and talked about.”

Henry Louis (“Skip”) Gates Jr. and Charles Ogletree Jr., Dorothy Burnham noted, are the “newcomers” in terms of intellectual energy on the Vineyard. “We welcome them,” Dorothy said, “but they are keeping going what people like Genii Guinier started.”

She is survived by three daughters, Lani, Sary and Marie, and three grandchildren, Omar, Niko and Ewart.

A celebration of her life as a teacher, dancer, water colorist, lover of music and social activist will be held in Cambridge in September.

Aloha nui loa.