February 2013 marked the centenary of the birth of Rosa Parks, the African American seamstress from Montgomery, Ala., who became known as “the mother of the civil rights movement” after her courageous refusal to give up her seat on a public bus. The image of a tidy, genteel, quiet lady with her head held high remains emblazoned as a totemic image of the movement.

To celebrate, the post office issued a stamp with her image during Black History month. In the U.S. Capitol building’s Statuary Hall, a nine-foot bronze statue of Rosa Parks — with her hat, coat, and eyeglasses, clutching her purse and sitting on the bus in the iconic pose — was installed amidst tributes given by President Obama and many congressional leaders.

Civil rights historian and political activist Jeanne Theoharis marked the centenary by publishing The Rebellious Life of Mrs. Rosa Parks, the first comprehensive biography about one of the most celebrated figures of the 20th century. In doing so, the Brooklyn College professor set for herself a project that other scholars thought of as unnecessary. What more could be said about the unassuming Mrs. Parks? But even the title of Ms. Theoharis’s richly detailed, moving, and often shocking book sends a message about how little the American public actually knows about the real woman as opposed to the beloved icon.

Ms. Theoharis will share her insights with Vineyard audiences at the Martha’s Vineyard Book Festival on Saturday, August 3, at 12:30 p.m. at the Harbor View Hotel and on Sunday, August 4, at 10:30 a.m. on the grounds of the Chilmark Community Center. The opportunity provides the author with her first visit to the Island, and it’s one she is looking forward to, particularly because of the Vineyard’s history of a strong African American community.

The critical and popular reaction to The Rebellious Life of Mrs. Rosa Parks has surpassed the author’s expectations. Writing for The New York Times, Nell Irvin Painter described the book as “richly informative, calmly passionate and much needed.” Since Beacon Press published the book in January, Ms. Theoharis has traveled all over the country speaking about Mrs. Parks’s decades of political activism not acknowledged through her popular image.

“It’s amazing how people love her, and how much people want this,” Ms. Theoharis said. “People love taking something that’s familiar and then finding out that there are all these things you don’t know. But I also think there’s a hunger for this information, politically. There’s a hunger for role models, images of what righteousness looks like, and what action looks like.”

Ms. Theoharis was particularly gratified to receive a standing ovation from the board of the NAACP after a speaking engagement arranged for her by activist Julian Bond. Ms. Theoharis describes Mr. Bond as “kind of like my black dad” for his scholarship and mentorship during her undergraduate studies in African American history at Harvard. She has strong memories of learning about the Montgomery bus boycott through Mr. Bond’s classroom teachings, which were pivotal lectures for her.

“He did two days about the Montgomery bus boycott and he broke it down hour by hour, day by day,” she said. “It was revelatory for me because in slowing it down, you saw how people made a movement. Often when we tell these stories, it sounds like people are just born to it. [Martin Luther King Jr.] seems born to it. And then you actually look at it and it’s clear that people actually make things themselves. There are all these people and one talks to another. It took a tremendous amount of organization.”

That Ms. Theoharis’s biography is the first substantive scholarly biography about one of the most well-honored figures of the 20th century is surprising. Historian Douglas Brinkley’s biography in 2000 only began the work of debunking the Rosa Parks myth. Mrs. Parks herself participated with a young adult biography that Ms. Theoharis describes as making the central figure out to be a “children’s book hero” and celebrity rather than a serious figure.

The story widely told of Mrs. Parks and the 381-day Montgomery bus boycott is that of a tired woman returning home after a day of work, a woman so worn out that she refused to heed a bus driver’s order that the African American passengers had to stand, since the “white” section of the bus had filled up. Mrs. Parks’s activism on December 1, 1955 is depicted as an individual act stemming from exhaustion, but an act that was then taken up by the Montgomery community — in particular by a young Baptist minister new to the city, Martin Luther King Jr. As the movement grew, the popular myth has Mrs. Parks standing silent and smiling, a benign presence and reminder of the movement’s early days.

Ms. Theoharis makes clear that Rosa Parks’s activism was not a singular act. Mrs. Parks may have been tired but her exhaustion came after decades of work as a community activist on behalf of racial equality. Mrs. Parks volunteered at the NAACP and was frequently active in support of women who were mistreated for issues of race or gender. Her husband Raymond participated in the movement supporting the Scottsboro Boys. The author points out that Mrs. Parks’s refusal to move her seat was not, as is popularly thought, the first time an African American protested unfair treatment on the Montgomery bus lines. What worked with Mrs. Parks’s stance was that her public image made it easier to embrace the cause. Her outward serenity belied strong convictions and courage.

“What makes her act so courageous is that she and other people have done it before,” Ms. Theoharis said. “There’s no reason to believe it’s going to work. And on many levels, she doesn’t expect that it’s going to change anything but she just does it. And that’s what courage looks like.”

Of even greater interest to both Ms. Theoharis and to the reader is what happens after the boycott. Having lost their jobs in Montgomery, Mrs. Parks, along with her husband and mother, moved north to Detroit with the hopes of finding work. It would be years before either she or her husband would again be regularly employed, and the ensuing years were full of extreme poverty, mental anguish and poor health. As a genteel Southern lady, Mrs. Parks declined to speak about her hardships. She continued to stand in as a representative of the civil rights movement at rallies and marches, even when the NAACP refused to offer financial assistance after the family’s difficulties were made public by friends who sought a solution.

“Typically, when the story gets told, most people don’t know she went to Detroit,” Ms. Theoharis said. “Or it gets told as though Detroit is a vacation home for her, and then somehow it’s kind of a happy ending. But Detroit is not a happy ending for her personally. It’s very hard. And Detroit is a racist place. Being the activist she is, she spends the second half of her life fighting the Jim Crow laws in the North.”

Ms. Theoharis reveals surprising details such as Mrs. Parks’s admiration for Malcolm X, and her work with Black Panther leader Stokely Carmichael, who considered Mrs. Parks his hero.

Telling the story of the later years isn’t easy, and is one factor in why Ms. Theoharis’s book is the first of its kind. The author conducted exhaustive research in the archives at Wayne State University, where a collection of Mrs. Parks’s papers are located. But that archive was donated by Mrs. Parks in 1976. Because of a legal and financial battle over her estate, the rest of her papers and her personal effects are held in storage by Guernsey’s, a celebrity auction house. The price for the full lot is $6 to $10 million. A 60-page inventory of the holdings helped Ms. Theoharis to glean some information about what might be found, heightening a sense of the possibilities lost by inaccessibility.

“We don’t have access to any of it until the collection sells,” Ms. Theoharis lamented. “And even if it sells, we don’t know who is going to buy it and what they’re really going to do with it. There’s been no scholarly assessment of the collection. A scholar could come in and tell you things you don’t know, could make connections between what was learned in one decade from what came before or after it.”

Ms. Theoharis would like to access the voice of Rosa Parks’s later years through the papers in the held archive. Though she can place the aging activist in many places during the 1960s and 1970s, Ms. Theoharis doesn’t have a strong record of her voice from those years.

“She didn’t tell you things you didn’t ask about,” Ms. Theoharis said. “If I got to sit with her for a day, I’d like to ask her about her anti-Vietnam work, her work with political prisoners, the community work she did for Congress, and what she thought of Stokely Carmichael and Angela Davis.”

Mrs. Parks’s death in 2005 was marked by a series of homages, including a public lying-in-wait at the Capitol, attended by 40,000 people. Ms. Theoharis labels the outpouring of public mourning as a “narrative of national redemption.” Both in her writing and in conversation, she expresses frustration that the funerals of Mrs. Parks and Coretta Scott King were used as opportunities to overshadow the difficult conversations about race when Hurricane Katrina struck just a few months earlier. She is also cautious about where the national conversation on race is now, in the second Obama term, since many Americans felt that the election of an African American president meant a solution to the conversation on race.

“I think there’s a kind of hopelessness, or a sense that the system is so big and things are so entrenched that it’s just hard to even know where to go at it,” she said. Still, she finds hope that the activist spirit is finding new energy, citing political movements that have sprung up recently such as Occupy Wall Street and protests against mass incarceration and “the new Jim Crow.”

“I spend a lot of time talking with my students about feeling one’s power as an individual and in communities and small groups. We can see now what was very effective, and it all begins with these small groups of people.”

Jeanne Theoharis will speak at 12:30 p.m. on Saturday, August 3, at the Harbor View Hotel and at 11:15 a.m. on Sunday, August 4, on the grounds of the Chilmark Community Center.