Grade inflation is diluting the effectiveness of American higher education, according to a report that has heightened a debate about whether universities are coddling their students.
The report, by the American Academy of Arts and Sciences, says United States faculty have been trained to be so sensitive to students' feelings that they fear being critical during the evaluation process.
Grade inflation appears worst among members of the Ivy League, including Harvard, Yale, Princeton and Columbia universities. In 1966, fewer than a quarter of all grades given to Harvard undergraduates were As. That percentage is now about half.
The result, says former Harvard dean of arts and sciences Henry Rosovsky, who co-wrote the report, is "a system that fears candour".
Dr Rosovsky also blames grade inflation on the dilution of course content and the increasing tendency of high-priced universities to act like businesses that want to please their clients.
Previous studies have found that the number of top grades given out at US universities nearly quadrupled between 1969 and 1993, while grade-point averages overall rose by 15 to 20 per cent.
Dr Rosovsky and his co-author, University of Pennsylvania education professor Matthew Hartley, says these grade increases do not appear to have been justified, since scores on university admissions examinations declined during the same period.
Dr Rosovsky adds that universities have dropped foreign language, mathematics and science requirements, allowing students to "avoid difficult courses that were less suited to their abilities" - and to avoid the resulting lower grades.