In addition to the Square, the van travels to the Park Street T stop, a Central Square homeless shelter, Copley Square and Chinatown.
The Square has traditionally been the busiest stop for the van, Perella says.
"It's amazing that right in the middle of Harvard University there are all these homeless kids," she says. "It's a different world."
And as he watches the teenagers walk away across the Pit, into the dark, rainy night, Melchiono agrees.
"It's a silent epidemic," he says.
He gestures across the street at the gates to Harvard Yard. "You wonder what events in life led to this dichotomy, to some kids ending up here and some ending up over there," he says.
At 8:30, only the volunteers are left inside the van. They will head to a shelter and then to Chinatown before finally calling it a night at 10 p.m.
"I love this," says Melchiono, as he surveys the bright van interior. "I think of these kids as teachers. They can teach us so much, if we only open our eyes and ears to listen. I just don't think we do enough of that."