Rose Marie Flynn in 1964 with her eight children a year before her ninth was born. Flynn helped organize, lead, sponsor and participate in hundreds of demonstrations. (Family Photo)

In the workaday world, Rose Marie Flynn was a PhD chemist, a teacher at Montgomery College and a scientific program analyst at Goddard Space Flight Center in Greenbelt. At home, she was the mother of nine.

She made up songs for her children, played piano and gave piano lessons. When her husband was stumped on a crossword puzzle, she knew the right word.

But Dr. Flynn, who died Oct. 19 at age 86, was best known as a community activist and social gadfly. Over a half-century, she helped organize, lead, sponsor and participate in hundreds of demonstrations against racism, the war in Vietnam, the closing of homeless shelters and nuclear proliferation.

She marched in support of the rights of farmers and migrant workers, affordable housing, universal health care, a cleaner environment and rent control. In the late 1960s, when her children were young, she took them to antiwar rallies, where they were tear-gassed by police.

When she became a grandmother, Dr. Flynn took her grandchildren to street protests. She was on the national steering committee of the Gray Panthers, a senior citizens’ advocacy group. At 77, she climbed a ladder over an eight-foot fence to occupy the old Franklin School on 13th Street NW in protest of the city’s plan to discontinue sheltering the homeless there.

“If you don’t take care of the poor, there’s a problem,” she said at another demonstration around that time. “It’s just a crime.”

Angela Flynn said her mother wanted to create “a world where there was no social, racial, sexual or religious discrimination, no homeless, no one went hungry and everyone received decent wages.”

Dr. Flynn was involved with such groups as the D.C. Statehood Party, the Maryland Green Party, the D.C. Coalition for Housing Justice, Empower D.C., Justice for Janitors and the Nagasaki Peace Committee.

Her death from cancer was confirmed by her daughter Julie Burke. She died at the home in Bethesda where she had lived for almost 60 years, a home filled with an eclectic mix of secondhand furniture, art and souvenirs. She had been a resident of the Washington area since 1945.

Dr. Flynn, alongside her husband, Joe, began her career as a public protester in the late 1950s, just as the civil rights movement was heating up.

Her children remember their parents joining picket lines around Montgomery County’s Glen Echo amusement park to protest racial segregation; the park agreed to desegregate in the early 1960s.

The Flynns helped create Suburban Maryland Fair Housing, which attacked not only racial discrimination in housing but also restrictive covenants in deeds that excluded all but “white Christians” as purchasers.

“We went to so many rallies and demonstrations,” daughter Eileen Flynn wrote in an e-mail. “I remember rallies for the UFW during the grape and lettuce boycotts [and] for Nixon to end the war. My parents continued with a passion to fight any injustice they saw, day in and day out.”

Lucretia Rose Marie Rakela was born May 8, 1926, in the Northern California community of Marysville. Her parents were Croatian immigrants.

She graduated in 1947 from Trinity College in Washington and received a master’s degree in physical chemistry from the University of California at Berkeley in 1949. She received a doctorate in physical chemistry from Catholic University in 1959.

From 1969 to 1981, she was an assistant professor of chemistry at Montgomery College in Rockville. She was a scientific program analyst at Goddard Space Flight Center from 1981 to 1986. She also was a volunteer mathematics tutor and teacher in adult education programs.

At 5-foot-1, Dr. Flynn was said to have projected a commanding presence when she testified before official panels and agencies on matters of social justice.

For their years of civic activism, Rose Marie and Joseph Flynn were honored in 2003 by the group D.C. Jobs with Justice. Joseph Flynn died in 2011. They had been married 59 years.

Surviving are their nine children, Joe Flynn of Baltimore, Clare Rowland of Dunedin Fla., Lawrence Flynn of Greenbelt, Julie Burke and Monica Hayes, both of Bethesda, Susan Flynn of Manitou Springs, Colo., Eileen Flynn and Angela Flynn, both of Santa Cruz, Calif., and Stephanie Pettis of Washington; a brother; and seven grandchildren.

It was no easy task, trying to right the wrongs of the world while managing a household of nine children. But each child got a decorated birthday cake every year, and Dr. Flynn made a gingerbread house for the family every Christmas.

Somehow, dinner always got on the table at night. Sundays were reserved for a “real meal”: meatloaf, lasagna or a chicken cut up into 11 pieces. Fish on Friday night was a family tradition. The menu alternated between fish sticks and a dish affectionately known as “tuna glop.”