IN THE DARKNESS of night, the complaints were etched in chalk up and down the walkways of Swarthmore College, a 399-acre oasis of green quads and liberal student activism southwest of Philadelphia.

"Welcome to Swarthmore," said one of the scribblings that recently confronted students - and administrators - when the sun rose. "Home of my rapist."

The so-called chalkings, which infuriated Swarthmore's president, were a turning point in a controversy that has rattled one of America's top-ranked liberal-arts schools. It has also placed female students there on the cutting edge of a national movement - charging that colleges and universities are systematically ignoring, downplaying and underreporting sexual assault and sexual harassment.

Hope Brinn says administrators were dismissive after a male student showed up in her room when she was unclothed and refused to leave, and Mia Ferguson says she was an assault victim. The two 19-year-old sophomores organized 20 other students and alums to complain to federal authorities that Swarthmore is violating the 1990 Clery Act that requires full reporting of campus crimes, including sexual assaults.

"Swarthmore will lead on this issue," said Ferguson, an engineering major who was born in England and grew up outside Boston. She acknowledged that their complaint that Swarthmore is soft on alleged perpetrators of sex crimes and underreporting incidents is at odds with the Delaware County school's reputation as a liberal oasis - one of many contradictions in a controversy that has now sparked campus protests and teach-ins.

About the only thing everyone agrees on is that underreporting sexual assaults and harassment is a national problem, not just a Swarthmore problem. On the same day as the Swarthmore complaint, 37 students and alums from Occidental College - the Southern California campus President Obama once attended - also lodged a Clery Act complaint, following complaints at a half-dozen other schools, including University of North Carolina and Amherst College.

Activists say a flurry of similar high-profile complaints is currently in the works.

Why now? Experts say some of the activism has been inspired by high-profile incidents - like the Steubenville, Ohio, case in which the community was accused of shielding a rape by high-school football players - and some stems from a change in the federal Title IX regulations on campus-sex discrimination, which has encouraged more complaints.

But much of it is rooted in a growing culture of young female empowerment in which activists connect through social media and go public with tales of rape and abuse that once would have been locked away in private diaries.

"It's almost like silence wasn't an option anymore," said Colby Bruno, managing partner of the Victim Rights Law Center in Boston and a leading authority on how colleges handle sexual assaults. Bruno and others said that for many years, women who'd survived assaults bought into a campus culture in which the concern was focused on the fallout that pursuing a case might have on the alleged attacker. But they say those attitudes are fading.

Swarthmore's Ferguson said that she told two dorm advisers during her freshman year that she'd been assaulted by a male student that she knew, but that the university didn't follow up on the complaint. She doesn't discuss her own case in great detail, but she is hardly shy in pursuing her complaint against the administration.

In a recent opinion piece in a student newspaper, Ferguson alleged that "members of the administration are pushing me into darkness" and concluded by listing her email address and phone number.

Her classmate Brinn is even more open in discussing how a male student first sent her some harassing emails this past winter. She said he finally entered her dorm room, uninvited, when she had no clothes on, and refused to leave. He left eventually without further incident, but Brinn - who hails from Wilmington, Del., and is studying education, anthropology and sociology - said that was only the beginning of her ordeal.

Suffering from panic attacks, she said she took her case to deans, a public-safety officer and the administrator tasked with compliance with the Title IX discrimination code, who greeted her with actions that struck her as indifferent or inexplicable.

Brinn said one key official laughed and said the man probably just forgot to knock because he was drunk, while another said an investigation would be "embarrassing" - for the accused. A dean sent out a "cease contact" email - addressed not just to the accused man, but also to her, "implying that in some way I was guilty for what had happened."

Swarthmore administration officials won't discuss the individual cases. In regard to the broader complaints, the college president, Rebecca Chopp, and others have both said Swarthmore needs to do better. The school has just hired an outside firm to review how it handles sexual-assault and harassment cases, but school officials insist that it already began making major improvements two years ago.

"We're doing everything in our power to prevent sexual misconduct and assault on our campus - and most importantly to support its survivors," said Nancy Nicely, Swarthmore's vice president for communications, who said that key personnel dealing with the problem have been replaced and campus training and other programs are expanding.

There is much at stake. If the U.S. Department of Education finds that Swarthmore violated the Clery Act, the college can be fined up to $35,000 for each violation, and the school could be suspended from federal financial aid programs.

Brinn and Ferguson say they are working on a second complaint that Swarthmore violated Title IX, the federal civil-rights statute. But the real prize here is the reputation - and drawing power - of a school that U.S. News and World Report consistently ranks one of America's top three liberal-arts colleges.

"Swarthmore is not alone in this," said Leslie Bell, a 1992 Swarthmore grad who's now a Berkeley psychologist and wrote on the controversy for Psychology Today, saying the college can and should do more. "It's endemic."