Joining "fellow members of the proud parents club," Vice President Biden told 150 graduates of the University of Pennsylvania School of Social Policy and Practice Monday night that each can serve as a beacon of optimism in difficult times.

"The thing that I love about you all . . . is that you believe in possibilities, the possibility that you can make things better," he said. He called that belief the "fuel" that has ignited social change.

Biden's daughter Ashley Biden, 28, received a kiss on the cheek from her father when she went onstage at Irvine Auditorium to accept her master's degree in social work. She was one of a dozen graduates receiving a John Hope Franklin Combating American Racism award. She specialized in macro social work with an interest in juvenile justice, poverty, and education.

Just before 6 p.m., about 1,250 relatives and friends of graduates started filing in through metal detectors and past bag-checking officers and at least one K-9 unit. The school, which has about 400 full-time and part-time students, is celebrating its centennial.

A few months ago, the school's dean, Richard J. Gelles, approached Ashley Biden about having one of her parents speak at the commencement. Ashley Biden agreed, Gelles said, that it would be nice to have her father speak.

Gelles said the dual role of father speaking to his graduating daughter and politician who has handled "many high-profile social-justice issues," such as the Violence Against Women Act in 1994, should make for a great speaker.

Biden said change comes through "one policy, one person, at a time," and made reference to the VAWA by saying: "One woman at a time."

He said part of his optimism stemmed from the election of Barack Obama, the nation's first African American president. For the inauguration in January 2009, Obama boarded a train in Philadelphia and picked up Biden at the station in Wilmington for the ride to Washington.

"I waited to be picked up by a black man, a black man," Biden said. "A man who 40 years ago could have not been able to stand at that platform in that environment."

Biden finished by saying that his late mother would have told the graduates that they are about to do God's work. "So go do it, do it well," he said to a standing ovation.