New York City Schools Chancellor Joel Klein told a group of mentoring supervisors that, if it weren’t for his mentors, he never would have envisioned the achievements he’s accomplished.

Klein delivered the keynote speech Wednesday at the 10th anniversary of the Mentoring Supervisor Certificate Program, a collaboration of the Graduate School of Social Service (GSS) and Big Brothers Big Sisters of New York City. Klein credited his high school physics teacher and others with making him who he is today.

“I grew up in Queens public housing,” Klein said, speaking at the Lincoln Center campus. “In my family, our vision was limited—when it came to college, everybody assumed I’d just stay on the course I was on (and not go). But there were a couple of teachers who changed my life by allowing me to stand on their shoulders and see a world that was just not visible to me.”

The renowned certificate program, which is sponsored by J.P. Morgan Chase, offers training in mentoring supervision through a 32-hour course that helps professionals develop youth mentoring within their agencies. The program is taught jointly by GSS faculty and professionals from Big Brothers Big Sisters.

Klein went on to graduate from Columbia University and Harvard Law School, and to become a Big Brother mentor himself. He urged the graduating class of 40 students to work on behalf of those students who have no voice in the system in order to achieve greater parity in education.

“I’ve discovered that mentors get more out of the experience than mentees,” he said. “And I’ve been on both sides.”

Peter Vaughan, dean of the GSS, said that 600 agencies have trained mentors in the joint program since its inception.

“We expect great things from you,” he told the graduating class.