But in a move that Hillel leaders say has been forced upon them by this generation's altered social landscape, the organization is throwing open its doors to everyone, designing programs that appeal to Jews and non-Jews and hyping its contribution to university -- not only Jewish -- life.
Examples of the shift are abundant.
Rabbi Joshua Feigelson, the self-described "campus rabbi" at Northwestern University, has designed a campus-wide program called "Ask Big Questions" that stresses the value of Jewish wisdom in addressing contemporary challenges. Other Hillel chapters are organizing interfaith programs, like Jewish-Muslim coexistence houses or trips to rebuild the Gulf Coast. And it's becoming more common to find non-Jews serving on local Hillel boards or as regular attendees at Shabbat dinners.
The shift is even evident in Hillel's changed mission statement. Prior to 2006, the organization sought to increase the number of Jews "doing Jewish with other Jews." Now it seeks to "enrich" Jewish student life, the Jewish people and the world.
"Most of the students that we have are not interested in doing Jewish with other Jews," Feigelson said. "They're interested in doing Jewish with their friends who are doing Catholic and Puerto Rican and Turkish -- their friends and their family. The challenge for us is how do you create expressions of Jewish life that students will deem to be authentic at the same time as they are not exclusive or tribal."
Beginning under the leadership of Richard Joel, Hillel: The Foundation for Jewish Campus Life sought to expand its reach beyond the minority of students with strong Jewish identities who naturally gravitated to the local Hillel chapter.
But Hillel leaders say increasingly that to reach the majority who might view the organization with anything from disdain to indifference, it must actively counter the perception that its chapters are "Jews-only" venues.
As it attempts to do so, Hillel finds itself negotiating a tricky line between Jewish particularism and universality, between the twin imperatives of creating uniquely Jewish programming and protecting the fluidity of personal identities that today's college students see as their birthright.
"We're in a world that has no boundaries -- no boundaries and infinite choices, literally," said Beth Cousens, Hillel's director of organizational learning and the author of a 2007 monograph, "Hillel's Journey: Distinctively Jewish, Universally Human," which lays out guiding principles for Hillel in the coming years.
"It is just dumb, it's counterproductive for us to create boundaries," Cousens said. "The way to make Jewish life vibrant, and help people fall in love with Judaism and discover who they are Jewishly, is not to be afraid."
Much discussion at Hillel's recent summit in Washington, D.C., focused on the peculiarities of so-called millennials, the generation born after 1980, and their unique set of cultural dispositions: globally minded, skeptical of institutional authority and unwilling to have their identities narrowly defined.
At the summit's opening plenary, Robert Putnam, the Harvard University professor who authored "Bowling Alone: The Collapse and Revival of American Community," described how he could name the religion of every person in his high school class because faith defined the limits of his generation's dating pool. High-schoolers today, he contended, couldn't perform a similar feat.
"It's not that people have stopped being religious, it's just not that big a deal anymore," Putnam said. "That line has been somewhat deconstructed."
For those who worry about the threat of intermarriage to Jewish continuity, the rise of the millennial generation, and Hillel's response to it, is likely to keep them up at night.
Hillel responds that it simply has no choice, that if an intermarried couple doesn't meet at Hillel, they will meet at a party or in the classroom where the organization will have no influence on them.
"Hillel is acknowledging that we don't live in a Jewish bubble," Cousens said. "If we don't do this, we'll be irrelevant."
Putnam has written extensively on the decline of community in America, and he urged the 675 summit participants -- most of them Hillel professionals -- to look for ways to create social connections that stretch across the boundaries of race or ethnicity.
In interviews on the sidelines of the summit, evidence emerged to suggest that process is already well under way.
At Syracuse University, the election of a non-Jewish student to the Hillel board occasioned some opposition. But while a meeting must sometimes pause to explain a particular Jewish phrase or practice, student leaders mostly say the addition has been positive.
"I think it's been a mutually beneficial experience for not only him and the board, but for also the community at large to see that we've reached beyond the Jewish student, that we've reached beyond what Hillel's stereotype is, and to bring in other types of people, and to really let ourselves realize that Hillel isn't just for one type of person," sophomore Jillian Zarem said. "It's for as many different people as we can reach out to."
At the Jewish University Center of Pittsburgh, a Korean student who regularly attended Shabbat dinners at Hillel managed to recruit his Jewish roommate who previously wouldn't set foot inside the building.
"How did he do it?" asked Aaron Weil, the executive director of the Pitt center. "He said, 'John, I'm a Baptist. I'm Korean. I'm going to Hillel. Don't you think it's a little bit odd that I'm willing to go to Hillel and you're not?' He didn't have a comeback for that, and he came in and saw the open community."
"The benefit to us," Weil continued, "is by making ourself a place that is open to all, Jews are going to feel more comfortable to go there because they're not going to a place that is Jewish only. Jews are looking today, in general, for opportunities to be Jewish but not to be separate."