“He told me a little bit about capitalism, how it’s a dog-eat-dog society, and that you couldn’t believe the capitalist press, it was all full of lies,” Ms. Piven said. “I said, ‘Why do you read the newspaper, Daddy?’ Because he read it — he really read it. And he said, ‘I read between the lines.’ Being literal-minded as little kids are, I tried to do that. I tried and tried.”

Rebelliousness came to her early. In elementary school, she refused to say the Pledge of Allegiance, even after being forced to stand in a corner with her face to the wall. “I said I could only pledge allegiance to the Maple Leaf,” Ms. Piven recalled. “I was a Canadian.”

In 1962, she started working at Mobilization for Youth, the New York antipoverty program that became a model for President Lyndon B. Johnson’s War on Poverty. Soon, she was observing rent riots and watching speeches by figures such as Malcolm X. She said that once, while standing guard outside a student-occupied building at Columbia University, she was attacked by the police.

During the welfare rights movement of the late ’60s and early ’70s, Ms. Piven repeatedly stormed welfare centers with other activists to demand benefits — including on her birthday, which led to her arrest. “Know what he said?” asked Ms. Piven, recalling her talk with the policeman. “‘You must be a very nice person to do this on your birthday.’”

All of these experiences showed Ms. Piven the art and power of political confrontation. “The streets of New York, the streets of the Lower East Side, the streets of Harlem — you could feel the energy almost crackling,” she said of her early days in politics. “That assertiveness came with anger, and a certain violence.”