It was a Thursday evening on the Columbia University campus, and a group from the Kappa Alpha Theta sorority was wedged onto couches eating takeout, some seated cross-legged on the floor. Two discussed an introductory Chinese language class. One thanked a sister for passing along her résumé for an internship. And then there were a few talking about spring break.

They had gone to Cabo, that cliché of a college pilgrimage in which a once-sleepy Mexican village becomes a hormone-fueled frat row, and you never, ever let your drink out of your sight (and if you do, you dump it). Except the women weren’t recounting drunken hookups or how many shots they’d taken on the beach. They were discussing “toxic masculinity,” the “privilege” that allowed them to be there and the “risk team” they put in place to look out for one another if anybody got too drunk or separated from their group.

When, at a beachside bar, a drunken bachelor tried to playfully bite — yes, bite — one of the women’s arms (“Who does that?” she asked), they staged an intervention. “What makes you think she wants to be touched?” her friend said, girl posse in tow, lecturing him on respectful personal space.

Later, when they stumbled upon a twerking contest on the beach (women twerking, the crowd judging), one in the group couldn’t help herself. “Don’t you find it problematic that there are no men up there?” she said to any stranger who would listen. “I think we felt empowered to speak up because we knew we had each other’s backs,” she recalled, seated on a sorority house sofa.

She later posted photos from the trip to Facebook: girlfriends with bronzed shoulders, guacamole and a casual shot of her beach read: “The Grounding of Modern Feminism,” by the Harvard historian Nancy F. Cott.

There was a time, not so long ago, when no self-respecting feminist would be caught dead in a sorority. “In my day? No way in hell!” said Sally Roesch Wagner, a women’s studies scholar at Syracuse University, who graduated in 1969. “Sororities represented to me as a feminist what beauty pageants did: women who were caught in the ‘get pretty, party, get a guy, get married’ syndrome that we were trying to break out of.”

That was certainly my stance back in 2002, as a sophomore at the University of Southern California. I transferred colleges, in large part because I so detested that school’s suffocating Greek life — giving up a scholarship, taking out a loan and moving to a city I’d never visited to try to find friends (and a social life) I didn’t have to “pay” for. Sororities, at least the traditional ones, were precisely the kind of classist, exclusionary groups that feminists fought against. Right?

It is puzzling, then, to discover that even amid the debate about campus sexual assault, and the role that Greek life plays in it, sorority enrollment is at a record high.

At the 26 historically white sororities that make up the century-old National Panhellenic Conference — and to be clear, this group does not include academic or multicultural sororities, like the popular African-American or Latino groups, which have their own governing bodies — enrollment has increased more than 50 percent over the last decade, outpacing the growth in college enrollment. And not just on the campuses you’d expect. At the Ivies — those institutions that long considered themselves just a hair too progressive for the pomp and ritual of sorority life; where women rushed to “The Vagina Monologues,” not the local frat mixer.

Harvard doesn’t even recognize Greek life on campus, yet this is the third year in a row that sorority enrollment has peaked, with 280 women seeking entrance to one of the college’s four chapters this year. Of those who rushed, 193 were offered bids, “a significant increase from the 150 women that constituted the average rush class size before 2011,” The Harvard Crimson wrote.

The numbers are similar at Brown, a place where Greek life was long considered so insignificant that a 2002 graduate, when asked about the trend, said, “Brown has sororities?” (This year, 293 Brown women rushed, about a 42 percent increase over last year.)

And at Yale, students voted to bring a fourth sorority to campus this year to contend with growing demand. “I believe it, women flocking to sororities, but it’s depressing,” said Kristin Houser, a Seattle lawyer and a 1971 Yale graduate. “I think the world feels so overwhelming that people want to return to traditions that seem comforting and provide structure and social support. But there was a reason that we rebelled against all of that.”

And then there are the New York schools: all-women’s Barnard, which banned sororities in 1916, calling them “elitist,” and Columbia, where a recent student newspaper article, “35 Ways You Know You’re a Columbia Student,” listed No. 26: “OMG YOU WOULD NEVER GO TO A FRAT PARTY. You are so above Greek life.”

Except that actually you probably would go to a frat party (see No. 27: “Sorry, how did you end up at Beta house?”) because sorority enrollment is unprecedented at Columbia, too — more than tripling over the last decade, “a growth unmatched by fraternities or multicultural groups,” according to The Columbia Spectator. At Barnard — which allows students to pledge at neighboring Columbia — 20 percent of the student body is Greek, according to the Columbia Panhellenic Council, which monitors sorority life on campus.

It has left many people baffled. “Honestly, when she first brought it up, my interior reaction was, ‘Over my dead body!’ That’s how strongly I felt that Greek life was an abomination,” said Susan Ruderman, a 1984 graduate of Harvard College, whose 18-year-old daughter — in the midst of the college application process — informed her that she was considering rushing. Ms. Ruderman, who works in philanthropy in Newton, Mass., said her first thought was: “Where did I go wrong?” — though she has slowly come around. “Funny how much principles ‘evolve’ when it comes to the happiness of one’s daughter,” she said.

When Amulya Kandikonda, a Barnard sophomore, told her friends back home in Illinois that she was pledging, “They were like, ‘You’re not white, you’re not tall and blond,’ ” she said. Which was not dissimilar from the experience of her sorority sister, Jennifer Egbebike, whose parents are Nigerian, but who grew up in Miami. “I was very hesitant to join, because I’m not a ‘typical’ sorority girl,” she said.

“Every year, we graduate these incredibly strong, talented, creative, activist women — proud feminists — and then they come back home to visit, and they’ve pledged,” said the historian Barbara Berg, a women’s history teacher at an all-girls private school in Manhattan and the author of “Sexism in America: Alive, Well, and Ruining Our Future.” “I was surprised, but over and over again I hear the same thing: It’s not as exclusionary as it used to be, it’s supportive, and it’s going to lead to other possibilities after graduation.”

“What I would love to think is that it’s not your mother’s sorority anymore. That it has evolved.”

On some campuses, anyway, that may be true. Words like “safe space,” “hegemonic masculinity” and “intersectionality” roll off these women’s tongues. Gone are the campy sorority jobs of yore — replaced by titles like “C.E.O.,” “C.O.O.” and “Chief Marketing Officer” to look better on a résumé. They read each other’s cover letters and tell each other to “send me your résumé, I’ll pass it along,’” said Oladunni Ogundipe, a Columbia senior. They are also in the midst of a robust debate about transgender inclusion.

“There are a lot of us who say openly that we are feminist, but even when we don’t, I think it’s implied in our interactions,” said Julia Wu, a Brown junior who is originally from Brazil. She recently hosted a “Lean In” workshop at her sorority, which she opened by telling the group, “There are more men named John than there are women who run companies in this country.”

At Theta at Columbia, “sisterhood events” — monthly camaraderie-building gatherings that are typical of sororities — take the form of presidential debate watching parties and a recent alumni networking brunch. There is no “pomping” — a ritual that involves weaving tissue paper to create elaborate floats and displays. But there are mandatory workshops on sexual consent and bystander intervention.

“I grew up in the South, so going to college I never expected to be a part of a sorority because I did think it was antifeminist,” said Blair Wilson, a Barnard sophomore. “But when I came to school, all the women I looked up to—those involved in student government, in sexual violence response, in different political groups—were involved.”

Last year, as Columbia erupted in debate over Emma Sulkowicz — the young woman who carried a mattress around campus to protest the university’s handling of her sexual assault complaint — members of the chapter signed their names to a donated mattress and carried it to a rally in support.

“We definitely still have to defend ourselves,” said a Barnard sophomore, Ilina Odouard, a neuroscience and behavior major. “But I almost feel more into feminism after having joined Theta than going to Barnard.”

Sororities did in fact begin as feminist organizations – a way for women, in the early days of coeducation, to band together inside hostile institutions. As the historian Diana Turk has chronicled in her book, “Bound by a Mighty Vow: Sisterhood and Women’s Fraternities, 1870-1920,” the first known Greek letter sorority — or “women’s fraternity,” as it was known — was formed in 1870. The early organizations were not overtly political, but their members often were: active in the suffrage movement, determined, as Ms. Turk put it, to prove themselves intellectual equals to men.

“This was a time when female students often had to sit in the back of the classroom, when they were often ignored by the male faculty, or addressed as ‘Mr.,’ even in coed institutions,” Ms. Turk said. “So I know that that can sound strange to some people, that early sororities acted in feminist manners before feminist was even a word, but these were women who were really trying to expand the boundaries of what was considered O.K. for women to do.”

It was later, in the early 1900s, that the social aspect (parties, mixers) and outwardly exclusionary policies of these groups began to make it on the books, said Ms. Turk — a result of education access expanding beyond the white upper class (and, thus, a need to keep those other women out). These policies would give rise to the first African-American and Jewish sororities — founded at Howard University and Barnard — which remain vibrant today.

But among the traditionally white groups, residuals of that history, and modern twists to it, remain: As recently as three years ago, two black women were denied sorority entry at the University of Alabama; at my alma mater, a recruitment email was recently leaked, containing a PowerPoint of 25 different shades of turquoise and the nine that members were allowed to wear (yes to “bezique,” no to “aqueduct”). Tales of binge drinking, bullying, hazing … the list goes on.

“On the first day of my recruitment weekend, I was greeted by about 40 sisters in matching outfits and heels,” said Anushua Bhattacharya, a Columbia senior who wrote an article about deactivating from Sigma Delta Tau. “I returned to my room that night feeling as if I had just finished the first round of a beauty pageant.”

Even at progressive campuses, tradition remains: fines for missing meetings; elaborate rituals; bans on serving alcohol at parties — putting fraternities in control of social life. And, of course, the barrier to entry: the class issues, the cost; being chosen, or cut, based on no formal criteria.

“It’s kind of like the white wedding,” said Caitlin Flanagan, an author who spent a year investigating fraternity life for The Atlantic. “You see these really empowered women, feminists, and you’re like: ‘Wait, your dad is walking you down the aisle? What?! And the guy you’ve been living with has to go and ask him permission?’”

The setup of Panhellenic sororities is complicated, but it’s not unlike Ms. Flanagan’s analogy — involving multiple governing bodies, bylaws and constitutions that sometimes haven’t been updated in a century. So while Columbia women can, for instance, individually reach out in support of Ms. Bhattacharya, who wrote about deactivating, they will also tell her they’ve been advised not to share the article on Facebook. The women of Brown may decide, as part of a student vote, to open up its system to transgender women, but the national chapters of the sororities could institute their own policies at any point. These groups can work to diversify their membership — and in many cases, they have — but most are still governed by a majority of white women more than twice their age.

“It’s difficult for sororities to move forward when some influential adults’ warped values are holding them back,” said Alexandra Robbins, a Yale alumni and the author of “Pledged: The Secret Life of Sororities.” “They can be as progressive as they want, but at the end of the day, nationals can still say, ‘You have to wear makeup or look a certain way.’”

For generations past, perhaps the only way to reconcile that gap would have been to reject the system. To opt out. “To us, it just seemed like one more way of the white male establishment consolidating its power, and we were having none of it,” said Ms. Houser, the Yale graduate.

Yet nearly every American president has been involved in Greek life. Fraternity alumni make up a large chunk of Fortune 500 C.E.O.s. Tales of frat-house-startups-turned-Silicon-Valley-successes (think Snapchat, Facebook, Instagram), as well as secret Wall Street handshakes, are simply par for the course.

And so: If you’re an ambitious Ivy League woman, if you buy into the belief that the best way to fight the system is to grasp power within it — or, as one woman put it, “tear down the patriarchy from the inside” — then maybe, as Ms. Robbins suggested, it’s no surprise “you’d want to counter what’s clearly a thriving, successful old-boys network.”

Ms. Berg said, “Perhaps part of this allure is that women want that network, too.”

Last year, when it was revealed that the National Panhellenic Conference — along with its fraternity equivalent, the North-American Interfraternity Conference — had spent thousands lobbying for a campus sexual assault bill, several sororities broke rank to come out in protest, pressuring the N.P.C. to withdraw its support. (The bill, called the Safe Campus Act, would have blocked colleges from investigating sexual assault claims unless a victim also reported the crime to law enforcement.)

At Dartmouth, a number of sororities have “gone local,” or disaffiliated from their national chapters, giving up funding in order to create their own rules. (At one, Sigma Delta, women hold parties with alcohol, with female bartenders, female door monitors and women designated to remain sober and monitor the scene.)

Other groups have said they’ve removed portions of their rituals — say, a reading from the New Testament — in an effort to be more inclusive. When, at one sorority, an invite to a “crush event” indicated that members needed to bring a male date, members pushed back — and the policy was changed to allow a date of any gender (or no gender, or date, at all).

When the women of Columbia’s Theta chapter decided to decorate that mattress, standing front and center at a rally on campus, they made the conscious choice to use the sorority’s motto — “Leading Women” — rather than their Greek letters, so as not to cause a stir within their national office.

“One could argue, that as feminists, maybe we should push back, maybe we should be trying to tear down these systems of supposed oppression,” said Annika Reno, a human rights and political science major at Barnard, who gathered recently with a group of sorority women to discuss feminism and Greek life. Hosanna Fuller, a senior majoring in computer science, added: “What if the goal was changing how Greek life operates as a whole? Like what are our actual goals? How can we track success?”

“I was saying all through recruitment to anyone who would listen, ‘I’m going to get in this system and I’m going to turn it on its head,’” said Jamie Fass, a Barnard first year and new pledge. “I think the world is working in a way where if we want to be competitive, it’s better to be competitive within the system.”

“It is an imperfect system for sure,” echoed Jing Qu, a political science and women’s studies major at Columbia. “But I think our generation is working to change it from the inside.”