Dolezal, 37, who served as president of the Spokane chapter of the National Association for the Advancement of Colored People, the nation's oldest and largest civil rights organization, said the controversy over her race had shifted dialogue away from key social and political issues.
"It is with complete allegiance to the cause of racial and social justice and the NAACP that I step aside from the presidency and pass the baton to my vice president, Naima Quarles-Burnley," Dolezal said in a statement on the NAACP Spokane chapter's Facebook page.
Dolezal came under intense scrutiny last week after questions emerged about her racial background and a Caucasian couple who identified themselves as her biological parents said she had misrepresented her ethnic background.
Dolezal, who also holds a post in Spokane's city government, identified herself as white, African-American and Native American on her application, City Council President Ben Stuckart said last week.
He said the city had opened investigation of the veracity of her application. Stuckart said Dolezal had filed police complaints of racial discrimination, most recently that she received hate mail.
In announcing her resignation from the NAACP, Dolezal said she had remained quiet through the controversy out of respect for the work of the civil rights group.
"The dialogue has unexpectedly shifted internationally to my personal identity in the context of defining race and ethnicity," she said. "I have waited in deference while others expressed their feelings, beliefs, confusions and even conclusions - absent the full story."
A Montana couple who identified themselves to media as Dolezal's parents has said the family was of European and Native American descent. They told CNN and Spokane media they had lost touch with their daughter but that she had showed an interest in diversity and black culture, especially after the couple adopted black children.
Responding to the growing controversy last week, the NAACP issued a statement saying racial identity was not a qualifying criteria for leadership. It also said it stood behind Dolezal's advocacy record.
Dolezal holds a master's degree from Howard University, a historically black university, and is a professor in the Africana Studies Program at Eastern Washington University, according to the university website.