Students walk through campus at Princeton University in New Jersey. (Mark Makela For The Washington Post)

Vassar College, founded at the outset of the Civil War to educate women, remade itself in 1969 when it admitted men for the first time. Then, the liberal arts school in Poughkeepsie, N.Y., reinvented itself again in 2007.

That’s when the college adopted “need-blind” admissions, offering seats to qualified applicants without considering whether, or how much, they could pay. The policy required the college to make a substantial investment in financial aid, and it produced a revolution in the school’s demographics.

In 2007, 12 percent of freshmen entering Vassar had enough need to qualify for federal Pell Grants. Within two years, the share had climbed to 20 percent and federal data showed it has stayed above that threshold ever since. In 2015, the Pell share for Vassar was 23 percent.

Vassar is one of 39 nationally ranked schools with Pell shares of at least 20 percent in their freshmen classes in 2015, out of about 150 The Washington Post examined. Eighteen of those schools are, like Vassar, private.

Catharine Hill, president of Vassar from 2006 to 2016, said the school’s record shows it is possible to broaden the demographic base of a selective college — drawing more students from low- and moderate-income families — without compromising standards. “In most cases, if you wanted to do more, you could do more,” Hill said. “All we had to do was go looking for kids. Our academic credentials actually went up.”

Here is a sortable chart with The Post’s analysis. It includes schools that U.S. News & World Report ranked this year among its top 100 national universities or top 50 liberal arts colleges (excluding federal service academies at West Point, Annapolis and Colorado Springs because they do not charge tuition). The chart shows fall 2015 Pell freshmen percentages, and percentage-point changes from five years earlier.

The lowest Pell share on the list belonged to Washington and Lee University — 6 percent. Will Dudley, who this year became president of the private Virginia liberal arts school, said the share rose to 11 percent this fall and he wants to lift it further. Dudley said he raised the issue of socioeconomic diversity at Washington and Lee when he was interviewing for the job. Previously, he was provost at Williams College, which had a far higher Pell share in 2015 — 22 percent. “If they didn’t want to make progress, they wouldn’t have hired me,” Dudley said.

Six other schools posted single digits for Pell share in 2015: Colby College (7 percent), Scripps College (8 percent) and Oberlin College, the College of William & Mary, Tulane and Southern Methodist universities (all with 9 percent).

Colby College said its Pell share has since doubled, to 14 percent. “We want to ensure that the most talented students from every background have access to this extraordinary education,” said Matt Proto, vice president for admissions and financial aid at the Maine college.

Binti Harvey, a Scripps spokeswoman, said the California college had a 10 percent Pell share this fall and considers economic diversity a top priority for recruiting. “At Scripps, we admit fewer Pell students because we meet the full need of a student rather than leaving a substantial portion for the student and their families to cover with loans — a common practice at many institutions,” Harvey said.

William & Mary said its Pell share this fall is 12 percent and that the college is “absolutely committed” to improving socioeconomic diversity. “We have made some progress in recent years, but this is an area in which we understand we must do better,” said Tim Wolfe, associate provost for enrollment and dean of admission. He said the public college in Virginia aims to raise money to boost financial aid, giving it a better shot in competition for out-of-state students from low-income families.

Within the Ivy League, Pell freshman shares in 2015 broke down like this, from largest to smallest:

  • Columbia, Princeton and Yale universities: 17 percent
  • Harvard University: 16 percent
  • Dartmouth College and Cornell University: 15 percent.
  • University of Pennsylvania: 14 percent
  • Brown University: 13 percent

Princeton’s rate rose to 22 percent this fall, a jump reported this week in a Washington Post article. Harvard said its rate is now 17 percent.

“We feel pretty good about the increase in socioeconomic diversity,” said Sally Donahue, director of financial aid for Harvard and a senior admissions officer. “Could we do better? Sure. We try every year to cast a wider, deeper net.” Harvard takes steps to analyze the socioeconomic background of its applicants before making decisions, Donahue said, part of what is known as a “holistic” review. “An inability to pay is not at all an impediment,” Donahue said.

Yale officials pointed out that the Pell statistics don’t include a large bloc of students from outside the United States with significant need. “Yale is one of only a handful of American universities able to offer a need-blind admissions policy for international students, and, as a result, we are one of the few American universities with an international student population that is truly socioeconomically diverse,” said Jeremiah Quinlan, dean of undergraduate admissions and financial aid.

Brown spokesman Brian Clark said the university — with a freshman Pell share of 14 percent this fall — wants to raise that rate and is moving to boost financial aid. “In our recruiting efforts, we actively seek students from a wide range of backgrounds, including first-generation and low-income students,” he said.

Cornell’s Pell share dipped slightly in 2016, to 15 percent of freshmen. “Focusing on the percent is not particularly instructive for an institution the size of Cornell,” the school said. “With more than 14,000 undergraduates, Cornell is more than twice as large as most of our peer institutions in the Ivy League.” Cornell said it “continues to focus broadly on affordability for low- and middle-income families.”

Dartmouth said its Pell share remained at 15 percent this fall, not counting international and undocumented students who also have significant financial need. The college said it is also developing a “low-income predictive index” to help admission officers analyze applications in their quest to build a diverse freshman class.

Columbia said its Pell share held steady this fall at 17 percent of freshmen enrolled in its undergraduate college and school of engineering and applied science. The university in New York said it is “proud to have a diverse student body, with a strong history of admitting first-generation and low-income students.”

U-Penn.’s dean of admissions, Eric Furda, said the university, with more than 10,000 undergraduates, also produces every year a high number of graduates who were Pell grant recipients. But he acknowledged that the school wants to have a higher freshman Pell share than its rate of 13 percent in 2016 and 14 percent in 2015, and is exploring how to do that.

“If this is going to be the measure,” Furda said, “then just what we’ve been doing for 10 years is not going to necessarily be enough.”

Here are more reactions to the data:

    • Massachusetts Institute of Technology: Its Pell share is 20 percent, up 5 points since 2015. “We have been active in increasing the number of low-income students on campus, and have invested a lot of resources in this effort,” said Stuart Schmill, dean of admissions and student financial services. MIT stands apart from many other selective schools, he said, in how it treats applicants who are children of alumni. “It also helps us that we do not give any advantage to legacy applicants in our admissions process,” he said. That is a key distinction because so-called legacies do not usually come from low-income homes.
    • California Institute of Technology: Its Pell share fell from 16 percent in 2014 to 11 percent in 2015, then crept up to 13 percent last year. “Since we make financial aid decisions subsequent to and independent of admissions decisions, the fraction of Pell-eligible students varies from year to year and that is what the statistics reflect,” Caltech said.
    • Stanford University: Its Pell share is 15 percent, up 2 points since 2015. “Pell is an important factor in providing access and opportunity,” a spokesman said. But, he said, Stanford also wants to ensure that financial aid is available to a broad range of students in need, from lower- to middle-income families.
    • University of Notre Dame: Its Pell share now averages 11 percent. “We do want more Pell students,” said Don Bishop, associate vice president for undergraduate enrollment. “However, we also want to enhance their overall development and experience and not just the number of students in a headcount.” He said the school’s “highest priority” in its current fund-raising campaign is to raise $1 billion for scholarships.
    • Georgetown University: Its Pell share this fall is 13 percent. Charles Deacon, the longtime dean of admissions, said the school wants to raise the figure to 20 percent, but that will probably take several years and a major boost in financial aid and support services to ensure that students graduate.
      Deacon said top schools often compete with each other to land star students from low-income families. “We’re dealing with a pretty talented group,” he said. “They’re in relatively short supply, and as you can see, they’re in high demand.”
    • University of Virginia: Its Pell share has held steady at 12 or 13 percent for the last few years. Greg Roberts, dean of admission, acknowleged U-Va. has room to improve. But he said that as a public flagship, its enrollment to some degree reflects the relative wealth of Virginia compared to other states. “I strongly believe that schools are interested in diversity in many forms,” he said.
    • University of Maryland: Its Pell share was 14 percent in 2015, and more recent data were unavailable. Barbara Gill, U-Md.’s associate vice president for enrollment management, said Maryland is a fairly wealthy state. Historically, the public flagship has not offered the same level of need-based financial aid as some of its competitors. “Our big competitive disadvantage,” Gill said. But she said the university is intensifying its fund-raising to address that issue.
    • Duke University: Its Pell share this fall is 15 percent, up three points in two years. “The simple answer is, of course, it’s not enough,” said Steve Nowicki, dean of undergraduate education. He said Duke has taken a number of steps to lure students from low-income families, and it wants to do more. But he said the university also wants to ensure it has enough aid for middle- and upper-middle-income families. It’s a “disservice,” he said, “to only focus on the lowest end of the spectrum.”
    •  University of Chicago: Its Pell share this fall is 13 percent, up 1 point from the two previous years. The university said it “is one of a small number” of schools that provides financial-aid awards without requiring students to take out loans. “We intend to continue increasing support for students of diverse backgrounds and high ability,” it said.

Correction: A previous version of this story incorrectly attributed a quote from an official at the College of William & Mary. The quote should have been attributed to the associate provost for enrollment and dean of admission, Tim Wolfe, not to college spokesman Brian Whitson. This version has been updated.