The cause was complications from the rheumatoid arthritis that had plagued her for much of her life, said a son, Pablo Conrad.
Rich came of age during the social upheaval of the 1960s and '70s and was best known as an advocate of women's rights, which she explored in poetry and prose. But she also passionately addressed the antiwar movement and wrote of the marginalized and underprivileged.
Her intense critique of contemporary society combined with her political activism set her apart from other leading women poets of her generation, including Sylvia Plath and Anne Sexton. She attended rallies against the Vietnam War, organized poetry readings for peace and marched for women's rights — and urged every writer to address social injustice in their art.
In "On Edges," a 1968 poem about women's rights, she wrote:
taste blood, yours or mine, flowing
from a sudden slash, than cut all day
with blunt scissors on dotted lines
like the teacher told.
From her first book of poems in the early 1950s, Rich revealed her feminist bearings, and when universities introduced courses in women's studies, Rich was likely to be included.
"Adrienne Rich was a voice for the feminist movement when it was just starting and didn't have a voice," said Barbara Gelpi, a professor emeritus of English and women's studies at Stanford University who with her husband, Albert, co-edited the 1993 volume "Adrienne Rich's Poetry and Prose."
"She expressed the sources of women's pain when women were coming to a sense of their own history and potential," Barbara Gelpi said in a 2005 interview with The Times.
Rich was a major presence among post-World War II American poets, according to Albert Gelpi, an emeritus professor of American literature at Stanford.
Her experiences "resonated with the political and social environment of the time," he said. "That is what made her poetry so powerful."
Critics consider Rich's 1962 poem "Prospective Immigrants Please Note" to be one of her more enduring. It voiced "a dilemma that extends across time," according to Harvard's Vendler, and reads in part:
Either you will
go through this door