More than 50 students pitched tents outside the Science Center last night, sleeping beneath the stars to call for more affordable housing in Cambridge.

Protesters huddled together as the night grew colder, listening to brief speeches from students and community activists and distributing literature about the high cost of housing in Boston.

Warmed by hot chocolate and a home-cooked lentil stew, speakers urged Harvard and other Boston universities to take a more active stance in alleviating the city's current "housing crisis" by housing all their students and avoiding the displacement of existing housing by new construction.

Last night's sleep-out marked a major action for the Greater Boston Interfaith Organization (GBIO), a city-wide coalition of progressive groups concerned with housing and homelessness in the Boston area.

Students who slept outside the Science Center last night did so in concert with demonstrations on some 80 different college campuses throughout the nation. Yesterday marked the "National Student Labor Day of Action."

"We wanted to address these issues on a lot of different levels," said Stephanie C. Stallings '02, one of the organizers of the sleep-out. "We believe so strongly that it's wrong for people to be sleeping outside on the street that we're willing to sleep outside in the cold."

Last night's action began slowly.

A handful of students began to mill about outside the Science Center as the sun set at about 7 p.m., listening to music as they pitched a half-dozen spacious tents on the lawn.

They decorated benches with posters that listed principles they hope Harvard will adopt with respect to the provision of housing.

The resolutions called for Boston area universities to set a goal of constructing 7,500 units of new student housing over the next five years.

About 50 students assembled by the time the speeches began.

Carol J. Garvan '02 told the assembled crowd that Universities have great power to alleviate the current housing crisis, arguing that rents rise when universities don't provide housing for their students.

And universities like Harvard are huge landowners. Garvan pointed to Harvard's recent acquisition of more than 90 acres of land in Allston-Brighton, and said the University should use this land in ways that benefit the community.

"Harvard has been a leading force in making a good effort," Garvan said. "But there is still a lot of room for greater efforts to be made."

Affordable housing and living wage are just two sides of the same coin, said Progressive Student Labor Movement member Amy C. Offner '01, who elicited cheers and sympathetic hisses from the crowd as she called on Harvard to enact a living wage of at least $10.25 for all employees.

"We need more affordable housing and wages that can allow people to live in that housing," she said.

Community activists said they were surprised and heartened to see Harvard students so passionate about issues of homelessness and housing.

The handful of homeless people attending the sleep-out said it was particularly poignant for them to be invited to an action just outside the gates of Harvard Yard.

"You'd think Harvard would be a bastion of science, computers, conservatism and capitalism," said a homeless activist and housing advocate who said he goes by the name "Outrageous Raging Love." "This is a sacrifice for students to leave their warm dorms for a night. Maybe activism isn't dead after all."

Love, who held a brightly-colored sign reading "People for the Ethical Treatment of the Homeless," said he planned to spend the night outside the Science Center if he could find his way into one of the tents.

""This is a very spiritual experience," Love said, looking around at the students setting up camp for the night. "I've asked myself whether a homeless person would be welcome in this Yard. The answer tonight is a resounding 'yes.' That's a warm feeling."