Princeton University reduced the percentage of A grades given in undergraduate courses by 5.1 percent in the first year of a new grading policy meant to cut down on grade inflation, according to a report the university released this week.

The program, instituted in 2004, set the target number of A+, A, and A- grades at 35 percent for all undergraduate classes, and a target of 55 percent A grades for senior theses and junior projects. But the targets are only guidelines, so departments retain some flexibility in assigning individual grades and they are not required to meet the targets.

Several top universities have been under fire for grade inflation in recent years. At Harvard University, after national news coverage highlighted accusations of grade inflation at the nation’s oldest university, the administration reported that grades are on the rise and has committed itself to curb the grade spike.

Unlike Princeton and Harvard, Yale does not release statistics on the distribution of grades. Yale administrators have long said they do not think grade inflation is an issue at the University.

Princeton’s Faculty Committee on Grading — which was created to supervise the new policy — praised efforts by the departments to reduce the percentage of A’s given to students, or to prevent further grade inflation in departments where the percentage of A’s was already at or near the targets.

“After so many years of steady grade inflation, we have actually been able to move the needle in the other direction,” the committee members said in a joint statement.

Dean of the College Nancy Malkiel, who has a policy of not speaking to college publications outside Princeton, told the Chronicle of Higher Education that she was pleased with the results of the program.

“I think we’ve made very impressive progress in a short space of time,” she said.

The grading distributions were reported for all courses and broken down into four divisions: humanities, social sciences, natural sciences and engineering. All divisions except for the natural sciences saw a decline in the number of A grades assigned, because, according to the report, the natural sciences were closest to the grading targets before the policy was instituted.

The total fraction of A grades given to undergraduates at Princeton in the last academic year was 40.9 percent, compared to 46 percent the year before. Humanities departments gave out the most A grades of any division before the policy was implemented — 56.2 percent — but that was reduced to 45.5 percent last year. Social sciences departments cut the number of A grades from 42.5 percent to 38.4 percent, and A grades in engineering courses decreased from 48 percent to 43.2 percent.

Although the policy provoked strong student reaction when it was proposed two years ago, junior Mike Duane said the campus debate has quieted as his classmates have for the most part accepted the policy.

“Any way you look at it, more than a third of the class getting A’s is still a pretty good deal,” he said.

The policies used to implement the new policies varied across different departments and one of the missions of the Committee on Grading is to evaluate best practices and share those across the university.

The Molecular Biology Department, which like many other natural science departments met the grading targets before it became Princeton policy, has a curriculum committee that works to maintain grading standards, department chair Lynn Enquist wrote in an e-mail. A grading rubric is in place to evaluate independent work, and a faculty committee grades senior theses, instead of the student’s academic adviser.

“We are a large department with a number of well attended introductory courses as well as many upper level courses,” Enquist wrote. “We have a reputation for being a ‘tough major.'”

The Economics Department assigned target percentages for A grades for each course in the department, depending on the type of course and level of difficulty. Using a less formal process, no committees were set up in the English department to help implement the policy, but faculty members were reminded of the guidelines to encourage them to “resist the impulse to award high and higher grades for work we know is undeserving,” according to the committee report.