Barbara Ehrenreich, the journalist and author whose books sympathetically explored the lives of working-class Americans while challenging the systems that exploited them, has died at the age of 81, the New York Times reports.

Ehrenreich was best known for her nonfiction book, Nickel and Dimed: On (Not) Getting By in America, published in 2001. The book investigated how low-wage workers struggled to survive during the 1990s, commonly perceived as years of economic growth and prosperity in the United States. To research it, Ehrenreich took a series of jobs—as a waitress, housecleaner, and Wal-Mart employee, among others—to better understand the challenges faced by the working poor in maintaining housing, health care, and child care. The book became a popular bestseller and is now considered a classic of social justice reporting.

In a starred review at the time, a Kirkus critic wrote, “Sharp, empathetic, astute, Ehrenreich speaks loudly and eloquently for a group of workers who are often too tired and too manipulated to speak for themselves.”

The author was born Barbara Alexander to a working-class Montana family in 1941; her father was a miner and her mother a homemaker. Radicalized by the political movements of the 1960s, including the movement against the Vietnam War, Ehrenreich quit a teaching job and began contributing articles to Ms. magazine. She wrote numerous books, including Bait and Switch: The Futile Pursuit of the American Dream, Bright-Sided: How Positive Thinking Is Undermining America, Living With a Wild God: A Nonbeliever’s Search for the Truth About Everything, and Natural Causes: An Epidemic of Wellness, the Certainty of Dying, and Killing Ourselves To Live Longer.

Her most recent book, Had I Known, was a collection of her essays published in 2020. A Kirkus critic wrote, “With such relevance to fractured late-capitalist America, Ehrenreich’s work warrants renewed attention.”

Her son, journalist Ben Ehrenreich, shared news of his mother’s death on Twitter. He wrote, “She was never much for thoughts and prayers, but you can honor her memory by loving one another, and by fighting like hell.”

Ehrenreich’s admirers also paid tribute on social media. Writer Eyal Press tweeted, “It’s hard to overstate how invisible inequality & the working poor were when Nickel and Dimed was published, not only to Republicans but also to Clintonian Democrats. RIP to a great journalist whose work will continue to enlighten and inspire.”

Tom Beer is the editor-in-chief.