Pro bono might soon mean gratis, at least at Harvard Law School, where the administration has moved to waive third-year tuition for students who promise to work in the public sector.

The initiative, introduced by Harvard Law School Dean Elena Kagan on March 18, awards a grant to students who show a commitment to public service while they are in school. They accrue “credits” through participation in public service programs and a public service summer job for at least 10 weeks.

The school has a history of graduates working in public service, but said salary discrepancies between public-sector lawyers and those in private practice is widening, said Harvard Law School Assistant Dean for Communications Michael Armini.

“Students are inevitably steered away from public service jobs just because of the financial realities,” he said.

Armini said only 12 percent of Harvard law graduates go into government or nonprofit work.

“We are more concerned with having our graduates out there working in fields that can have an impact more than anything else,” he said.

Boston Bar Association spokeswoman Bonnie Sashin said for lawyers, graduating with $160,000 debt is typical.

“If people can get a job, especially a very well paying private-sector job, they are going to be able to pay their loans off that much faster,” she said.

The average amount a student in a private law school borrowed from 2005 to 2006 was $83,181, not including loans left over from undergraduate study, according to the American Bar Association.

Sashin said she hopes other schools will follow Harvard’s lead as a way to reduce the pressures of tuition debt and create a more diverse and sustainable public sector.

“It would be unfortunate for public sector jobs just to be limited to people who were independently wealthy or have a wealthy partner or spouse,” she said.

Mary Gallagher, Boston University School of Law Director of Marketing and Communications, said the university would like to encourage students to enter into the public sector because of the social benefits.

Suffolk University law professor Marc Greenbaum said Harvard’s new policy forces law schools to look at other options to relieve student debt, but some schools will be unable to adopt such a generous program and must look for other alternatives.

The program will strengthen government because lawyers in the public sector do some of the most important work that any lawyers do, he said.

“We all depend on government and unless the public sector can attract good people, and in particular lawyers, then the ability of our government to function is going to be impaired,” Greenbaum said.