Rosalyn Fraad Baxandall, or “Ros” to her friends, was a trailblazing second-wave feminist and a lifelong radical. Brilliant, glamorous, and spirited, she was a devoted activist and intellectual for over half a century, until kidney cancer cut short her life on October 13.

From the earliest days of the women’s liberation movement, she was a leader — active in New York Radical Women, Redstockings, No More Nice Girls, the abortion and reproductive rights movements, and more. In 1967, as a new mother and a staffer of Mobilization for Youth, she helped create Liberation Nursery, the first feminist day care center in New York.

Ros’s activism deeply infused her professional life writing and teaching about women’s history, especially the history of women in the American left and labor movements. She read voraciously and wrote quite a bit too. America’s Working Women, the book she coedited with Linda Gordon and Susan Reverby, is a classic; her work on Elizabeth Gurley Flynn, Words on Fire, is another.

For decades she was a beloved faculty member at SUNY (State University of New York) College at Old Westbury. After she retired in 2012, she taught at a women’s prison in Manhattan and in the labor studies program at the City University of New York’s Murphy Institute.

Ros was raised in a left-wing household, as she recounted in an essay coauthored with her sister in the 1998 volume Red Diapers. For her it was obvious that fighting for women’s liberation without simultaneously challenging capitalism made no sense. At the same time she understood from a tender age that the Left’s own commitment to gender equality was tenuous at best.

That perspective, which in the 1970s came to be known as socialist or Marxist feminism, was one Ros nurtured for the next half-century. She also helped communicate it to a new generation of radicals. Although the terminology is different today, the ideas persist in the framework of intersectionality.

Ros threw her whole heart and soul into the movement. “We were, we believed, poised on the trembling edge of a transformation,” she recalled in her essay in The Feminist Memoir Project , published in 1998.

For me, the women’s movement was love at first sight. The minute I heard about it, in 1967, I joined . . . Feminism solved my life’s puzzle . . . I’d been active in the civil rights and anti-war movements. Yet my activism in those movements flowed from obligation and outrage, not from a sense of my own struggle. Oh, the ecstasy and the agony . . . We expressed individual rage, but on behalf of a more communal political and economic radicalism than is imaginable now . . . We saw structures of race, class, and gender as interconnected, and we knew that social deformations had to be corrected through radical institutional transformation.

I am fifteen years younger than Ros, but as a student in the 1970s I too joined the socialist-feminist movement, and I was lucky enough to become one of her many friends when I moved to New York in the early 1980s. We worked together for years on the editorial collective for the New Feminist Library — a book series published by the Monthly Review press — and also attended a study group together for a time.

I remember many meetings in her apartment in Washington Square Village. In those days Ros was a towering figure for me, a political visionary and an intellectual live wire. Indeed, I found her totally intimidating. After I moved to the West Coast in 1988, I continued to admire her from afar.

I vividly remember when my son was born in 1992 and she sent me a baby gift with a note welcoming another socialist-feminist child into the world. Years later she presented a paper — a piece she never published — recounting the history of her day care activism at a conference in Madison that literally moved me to tears; I had cut my own political teeth on campaigns for day care.

We grew closer when I returned to New York in 2009 after a long absence. I visited her soon after at her summer home in Cape Cod, where she loved to have guests. The lively company that time included our mutual friend Sheila Rowbotham, the renowned English socialist-feminist writer, and several others drawn from Ros’s large circle of friends.

Ros had a razor-sharp mind, an extraordinary charisma, and a political commitment that never wavered. She mourned deeply as the women’s movement’s radical wing was marginalized and as conservatives ascended into power, but she never lost the faith. She will be deeply missed.