It started out as somewhat of a joke: What would happen if an all-boys prep school had a club for feminists?

Sitting in his living room one Saturday afternoon in September 2017, Matias Benitez, then a sophomore in high school, was talking to his older sister about a feminist club she had just joined at her school. Even at her large co-ed public high school, almost all of the members of the club were girls, she told him.

“Wouldn’t it be crazy if Regis had a club like this?” his older sister said, referring to Regis High School, the elite Catholic preparatory school Matias attends on the Upper East Side of Manhattan.

Matias thought back to a speech he watched years earlier by actress Emma Watson, whose campaign, HeForShe, aimed to galvanize men and boys to be advocates for gender equality. The club suddenly didn’t seem like such a crazy idea. An hour later, he texted his friend Matt Chen, a fellow Regis sophomore.

“We should start a he for she society,” Matias texted him. “Basically feminism.”

“That’s a great idea,” Matt responded.

Neither teenager could have predicted just how relevant the club would become. Less than a week later, the Harvey Weinstein story spurred the dawn of the #MeToo movement. And over the course of the next year, news such as the sexual assault allegations against Brett M. Kavanaugh would shed an unflattering light on the culture at elite all-boys prep schools — and on teenage boys in general.

For Matias, now 17, and Matt, 16, the way to tackle these complex issues — toxic masculinity, sexual harassment, gender inequality — is for teenage boys to be a part of the solution. They sought to change their classmates’ perceptions of feminism as solely a women’s issue, and to fill a gap in a high school curriculum that too rarely focuses on women’s history and gender issues, particularly at all-boys schools.

“People think of it as a movement for women by women,” Matias said. “It’s never supposed to be like that. You can’t make real change unless everyone is involved.”

Since launching the club, which they called HeForShe, one year ago, Matias and Matt have held weekly meetings with about a half-dozen other boys to discuss the biggest gender news of the day — everything from pregnancy discrimination to college sexual assault to the Boy Scouts’ decision to accept girls. They have hosted standing-room-only meetings during their lunch period, offering free pizza to draw crowds of upward of 40 boys.

In January, they led a group of high school boys to the Women’s March in New York City, and they are planning a trivia night in honor of International Women’s Day. Later this month, Matt and Matias plan to attend the United Nations Commission on the Status of Women.

When they started HeForShe, Matias worried that the club would be met with skepticism or pushback from people who felt boys shouldn’t be talking about feminism. He was surprised to see both the school’s administrators and the female students at a nearby all-girls school rally around the idea.

When the boys heard that some girls had felt uncomfortable and had been touched inappropriately at some of the Regis High School dances in previous years, the HeForShe club joined forces with the nearby Catholic and all-girls Marymount School to host a conversation about how to create a healthier environment at the school’s dances.

And amid the Supreme Court confirmation hearings for Kavanaugh, Matt and Matias organized another forum with students from Marymount to discuss harassment and sexual assault. The girls recounted instances when they had been harassed or groped, and one female student recalled being catcalled on the subway earlier that same day. Matt said he was stunned by just how frequent and common such experiences were.

“When I’m on the subway, I just put in my ear buds and close my eyes,” said Matt, who commutes to Regis about 70 minutes each day from his home in New Jersey. “I couldn’t imagine having to worry about someone violating my personal space in the way that they do every day.”

The group’s conversations have overflowed into the hallways and created ripple effects throughout the school, said Christian Mariano, assistant principal for student life at Regis. The Catholic prep school enrolls 534 boys, grades nine through 12, all of whom receive full scholarships and many of whom commute from at least an hour away, according to the Regis website.

Each year, the school chooses a social justice topic to focus on over the course of the school year and encourages students to nominate topics in a questionnaire. Ahead of the 2018-2019 school year, Regis decided to focus on women’s issues, a choice Matt and Matias think HeForShe helped set in motion.

Leading HeForShe has opened the boys’ eyes to the various ways — big or small — in which women and men are treated differently on a daily basis, even within their own school, Matt and Matias said. Matt thought back to freshman year, when he heard a classmate refer to a female teacher as “frumpy,” a comment that he felt would never be said about a male teacher.

“I remember hearing it and thinking, ‘I have never thought of a teacher based on their appearance,’” Matt said.

Matt said he has noticed his classmates criticize certain female teachers as being “too harsh,” even though there are equally strict male teachers. It’s a pattern he’s learned to spot: Assertiveness is often seen as negative in women but positive in men.

“I don’t understand that,” Matt said. “The only difference between those two teachers is their sex.”

Their leadership in the club has made both boys feel more comfortable speaking up when they hear their classmates make disparaging comments about women or the concept of feminism. They try to push back on the misconceptions that being a feminist means you automatically hate men, or that the improvement of a woman’s status is tied to the lowering of a man’s status.

“Feminism isn’t just by women for women,” Matt said. “It’s for everyone.”

Correction: An earlier version of this story erroneously attributed a quote about female teachers to Matias Benitez, instead of Matt Chen. This story has been corrected.