Betty Dodson, a feminist sexologist and evangelist of self-pleasure who taught generations of women how to masturbate in workshops, books and videos, seeing the do-it-yourself climax as a liberating social force, died on Saturday at a nursing home in New York City. She was 91.

The cause was cirrhosis of the liver, said Carlin Ross, her business partner.

Ms. Dodson was a second-wave feminist making erotic art when she began hosting consciousness raising groups — but with a twist — in her Manhattan apartment. The method involved a genital show and tell, so that women could see that vulvas came in all shapes, sizes and colors; this was followed by clitoral attention with a vibrator. As she refined her teaching, she realized that she had found her calling.

“This masturbation business,” as she liked to say, was a kind of social justice work. If women could learn to pleasure themselves properly, she reasoned, they could end their sexual dependence on men, which would make everybody happy.

“The most consistent sex will be the love affair you have with yourself,” she wrote in “Sex for One” a quasi memoir and how-to guide that began as a short primer in Ms. Magazine and that has been translated into 25 languages since Random House first published it in 1987. “Masturbation will get you through childhood, puberty, romance, marriage and divorce, and it will see you through old age.”

Gloria Steinem, a co-founder of Ms. Magazine, wrote in an email: “Betty Dodson was a brave and daring advocate for women’s right to sexual knowledge and pleasure. Her workshops turned women on to the beauty of our own bodies, and her outrageous honesty allowed more women to speak our truths.”

It was Ms. Dodson’s experience with orgies — group sex, in the parlance of the day — that brought home to her the fact that even in such a free-spirited setting, women were performing their orgasms and didn’t seem to have a clue about how to get there on their own. Also, she said, the women always ended up in the bedroom examining her collection of vibrators while the men talked shop — stocks and sports, mostly — in the living room.

“Organized group sex is a little bowling league kind of thing,” she told Enid Nemy of The New York Times in 1971. “It’s super‐compulsive — there’s a frantic quality to it. It’s weird.”

Ms. Dodson enraged some second-wave feminists, who conflated her work with pornography, a bugbear for that generation. (Her slide show of vulvas at a National Organization for Women conference was particularly controversial, though a vibrator demonstration was quite popular, and she sold out the box of devices she’d brought with her.) But later generations have been inspired by her sex-positive teachings, and the internet continues to buoy her fame and promote her mantra: “Better orgasms, better world.”

Carol Queen, a sex educator and activist, recalled meeting Ms. Dodson in the late 1980s as part of her doctoral work in sexology at the Institute for Advanced Study of Human Sexuality in San Francisco and being captivated. (Ms. Dodson would receive an honorary doctorate from the institute.)

“Once she was on this path, she absolutely embraced it,” Dr. Queen wrote in an email. “She found it important, she saw it was important to others, and that was it — she basically never stopped. Women flocked to her workshops, and some stayed around to develop their own styles of teaching, or activist work, or went back to school so they could be therapists or midwives or whatever style of work that would let them be themselves and make a difference. I’m not sure there’s anyone I know of in the sexuality activists of my generation who wasn’t inspired (and in many cases egged on) by Betty.”

Annie Sprinkle, the 1970s porn star and prostitute-turned-sex educator, was also a Dodson acolyte. “To teach sex in such an explicit hands on way requires enormous courage, experience and conviction,” Ms. Sprinkle said in a phone interview. “Betty had it all. She popularized the clitoris and clitoral orgasms and gave the clitoris celebrity status.”

Last year, at age 90, Ms. Dodson famously made the actress and entrepreneur Gwyneth Paltrow blush when Ms. Dodson appeared — gruff-voiced in her signature pixie cut and clad in a denim jacket emblazoned with patches (“Come Together,” read one) — on an episode of Goop Lab, Ms. Paltrow’s six-part Netflix series. She was there to explain her method and her workshops, now in their 50th year and taught not just by Ms. Dodson but by bodysex leaders, as they are known, all over the world.

What happens in a workshop? Ms. Paltrow asked Ms. Dodson. “Everyone gets off,” Ms. Dodson replied.

It was a remarkably moving and educational episode, which surprised many viewers, since Ms. Paltrow has promoted practices — vaginal steaming, for one — that have irritated sex educators, feminists and doctors. There was a lesson in female anatomy (the vagina and the vulva are different things, Ms. Dodson told Ms. Paltrow), a photo montage of vulvas and a finale that showed Ms. Dodson helping Ms. Ross, her business partner, achieve a climax.

Netflix declined to say how big the episode’s viewership was, but a spokesperson for Goop said that anecdotally it was the most popular episode in the series. Shown in a Manhattan movie theater last December, the episode received a standing ovation.

Betty Anne Dodson — she was proud that her initials spelled BAD — was born in Wichita, Kan., on Aug. 24, 1929. Her mother, Bess (Crowe) Dodson, worked in a dress shop; her father, Frank Dodson, was a sign painter and an alcoholic. She had three brothers, Rowan, Billy and Dickie, and leaves no immediate survivors.

Ms. Dodson said that she and her brothers played as equals when they were children, which not only developed her muscles but “added to my sense of entitlement as I got older,” she wrote in “Sex by Design: The Betty Dodson Story” (2010), her second memoir.

When she was in the ninth grade, she recalled, a family friend and drinking buddy of her father’s shoved his hand into her pants when she had asked to drive his car. She kept silent, she wrote, because she felt complicit in what she experienced as a transaction. But when the same man groped the breasts of her best friend in her kitchen, she threatened him with a knife. “You’d better get out of here before I shove this knife in your stomach,” she said she had told him.

In 1950, at age 20, Ms. Dodson moved to New York City to become an artist, supporting herself as a freelance illustrator of lingerie ads and studying at the Art Students League of New York. She married an advertising executive, but they were sexually mismatched, she said, and her unhappiness and shame about it accelerated her drinking. After they divorced amicably, she got sober, and it was in a meeting for alcoholics that she met a man who would teach her about self-pleasure. They maintained a sexual relationship until his death in 2008. (Ms. Dodson was essentially agnostic about the gender of her partners, describing herself as a “heterosexual bisexual lesbian.”)

Her art career floundered in the 1960s and ’70s — a representational artist of erotica was out of step with the art world’s appetites at the time. But the workshops were taking off.

Vibrators were the key to her method. Her first devices were the so-called scalp massagers of the day, but they got too hot — workshop attendees had to hold them with pot holders — and vibrated too powerfully. Once she found her go-to, the Hitachi Magic Wand — which she liked because it was easy to hold and dispersed its vibrations — she never looked back. She called it the Cadillac of vibrators. In the last decade or so, as the sex toy industry has evolved to produce ever more design-forward, feminized devices, the Wand retains a quaint, gawky look.

Eager for her imprimatur, manufacturers have regularly sent her products hoping for an endorsement. Ms. Dodson always tried every one, Ms. Ross said, but none was ever up to snuff. A curved wand came close, but its shape caused it to slip at the crucial moment and turn itself off. “I would never represent this product,” she told Ms. Ross, and tossed it in her “toy chest,” where she kept her collection of rejects.

“She could have signed on with any of the companies,” Ms. Ross said, “but you couldn’t buy her, and you couldn’t script her.”

In a profile that ran last March, just as the country was shutting down in quarantine, Ms. Dodson told Ruth La Ferla of The New York Times, “Partner sex, that’s over now. But I wouldn’t turn down a good-looking guy if he walked in now.”