Paula Weinstein, a movie producer, studio executive and political activist who became a fierce advocate for women in her industry, died on Monday at her home in Manhattan. She was 78.

Her sister Lisa Weinstein confirmed the death. She said the cause was not yet known.

In the boy’s club of Hollywood, Ms. Weinstein was the rare female top executive: Over her long career, she was president of United Artists, a vice president of Warner Bros. and an executive vice president at 20th Century Fox. She was just 33 when she was hired at Fox in 1978, and when she was promoted to vice president a year later, The Los Angeles Times called her “the highest-ranking woman in the motion picture industry.”

“A man can be mediocre in almost everything, but a women’s got to be perfect,” she told Life magazine that year, when she was included in an article about Hollywood’s “Young Tycoons.”

But Ms. Weinstein, who colleagues said possessed a wicked sense of humor — her sister described her laugh as an infectious cackle — and a steely commitment to social justice, was unusual in Hollywood beyond her gender. As Ken Sunshine, the veteran public relations consultant and longtime Democratic activist, put it in a phone interview: “Unlike so many, she didn’t play at politics. To her, social and political change was paramount. She was the antithesis of a phony Hollywood activist looking for good P.R. or a career boost. She was unique in a sea of pretenders.”

Activism was the family business: Her mother, Hannah Weinstein, was a journalist and speechwriter who in 1950 took her three young daughters to live in Paris and then London, fleeing the grim and punitive politics of the country’s McCarthy era. In Britain, where the family lived for more than a decade, Hannah Weinstein produced movies and television series using blacklisted actors and writers like Ring Lardner Jr. and Ian McLellan Hunter. She repeatedly told her daughters, as Lisa recalled, “If you believe in something, you have to be willing to get up off your ass and do something, and if you don’t get up off your ass, you really didn’t believe in it.”

“She was a daunting role model,” Lisa Weinstein added.

It was Hannah who steered Paula into the movie business, by way of Jane Fonda.

“Hannah was the first person I ever asked for money as an activist,” Ms. Fonda said in an email. “It was to open the G.I. office in D.C. in 1970, where concerns facing soldiers could be brought to Congress. She gave me $2,000 — astonishing in 1970. Some years later, Hannah called me to ask if I could help her daughter, Paula, who had just graduated from Columbia University, get a job in Hollywood. She said I ‘owed her one.’”

The two women then met for lunch at a Hamburger Hamlet in Los Angeles and were instantly smitten with each other. They were of like mind, both having been involved in the antiwar protests of the 1960s, and both with arrests under their belts — Ms. Weinstein’s for taking part in a protest at Columbia. Soon after, Ms. Weinstein became Ms. Fonda’s agent, helping her get the role of Lillian Hellman in “Julia” (1977), based on Ms. Hellman’s book “Pentimento.”

“It helped that Lillian was Paula’s godmother,” Ms. Fonda said.

Her next job was at Fox, where she oversaw the production of “9 to 5” (1980), the hit comedy starring Ms. Fonda, Lily Tomlin and Dolly Parton as office workers who revolt against their sexist employer. More recently, she reunited with Ms. Fonda and Ms. Tomlin as an executive producer of the long-running Netflix series “Grace and Frankie.”

Ms. Weinstein produced more than 30 films, including “The Perfect Storm” (2000), starring George Clooney as a Massachusetts fishing boat captain — and co-starring an epic nor’easter — as well as the comedy “Analyze This” (1999) and its sequel, “Analyze That” (2002), with Robert De Niro and Billy Crystal. She was also a founder, with Ms. Fonda, Barbra Streisand and others, of the Hollywood Women’s Political Committee, a fund-raising powerhouse for liberal candidates and causes from 1984 to the late 1990s.

With her husband, Mark Rosenberg, whom she met when they were both members of the national activist organization Students for a Democratic Society, Ms. Weinstein made a number of films, including “The Fabulous Baker Boys” (1989), with Jeff and Beau Bridges and Michelle Pfeiffer, and “Fearless” (1993), also starring Jeff Bridges. They also made “Citizen Cohn” (1992), an HBO movie about Roy Cohn, the lawyer and fixer for Senator Joseph McCarthy — a topic close to Ms. Weinstein’s heart, given her upbringing. Their final production together was “Flesh and Bone” (1993); Mr. Rosenberg died of heart failure at age 44 while working on the set of that film.

Ms. Weinstein continued to make films for Spring Creek Productions, the company she and her husband had formed — notably another HBO film, “Recount” (2008), a political thriller based on the hairline finish of the 2000 presidential election and Bush v. Gore, the Supreme Court case that decided the election in George W. Bush’s favor.

“Paula knew how to marry the commercial with the political,” said Lucy Fisher, the veteran producer and former vice chair of Sony Pictures, who considered Ms. Weinstein a mentor, “but not in a medicinal way. She invented the format that became HBO’s imprimatur, the high-quality but gossipy-behind-the-scenes drama.”

Paula Weinstein was born on Nov. 19, 1945, in Manhattan, the youngest of three daughters. Her mother, Hannah (Dorner) Weinstein, met her father, Isidore Weinstein, known as Pete, when they were hired as speechwriters for Mayor Fiorello La Guardia. At the time, Hannah was a reporter for The New York Herald Tribune and Pete was a reporter for The Brooklyn Eagle.

The couple had separated by 1950, and Hannah subsequently left the country with her daughters. They returned to the U.S. in 1962, and Paula enrolled in Columbia soon after.

In addition to her sister Lisa, Ms. Weinstein is survived by another sister, Dina, and her daughter, Hannah Rosenberg.

Since 2013, Ms. Weinstein had been chief content officer for Tribeca Enterprises, which includes the Tribeca Film Festival and Tribeca Studios, where she developed branded content and ran mentorship programs for emerging writers and directors. She left Tribeca last fall to focus on political work.

“I don’t want to sit on the sidelines and rail about everything. I really want to jump in, fully, into the campaigns. Both statewide and national campaigns,” she told Deadline magazine after her departure. “It just feels very much like a moment … between the climate, and book banning and everything else that I don’t need to go into.”

At Ms. Weinstein’s death, tributes poured in from her colleagues and friends, including from Debora Cahn, a writer and producer.

“Paula was a force of nature,” Ms. Cahn wrote. “She taught me so much about so many things. How to stand up and be the thing. Stand in front. Talk loud. Be outraged and happy.”