Claremont McKenna College, a small, prestigious California school, said Monday that for the past six years, it has submitted false SAT scores to publications like U.S. News & World Report that use the data in widely followed college rankings.

In a message e-mailed to college staff members and students, Claremont McKenna’s president since 1999, Pamela B. Gann, wrote that “a senior administrator” had taken sole responsibility for falsifying the scores, admitted doing so since 2005, and resigned his post.

People briefed on the matter said that the administrator was Richard C. Vos, vice president and dean of admissions, whose name was removed in the last few days from the college’s online list of top officials.

Mr. Vos, reached at his home Monday night, said: “No comment. It’s an internal personnel matter.”

The critical reading and math scores reported to U.S. News and others “were generally inflated by an average of 10-20 points each,” Ms. Gann wrote. For the class that entered the school in September 2010 — the most recent set of figures made public —the combined median score of 1,400 was reported as 1,410, she said, while the 75th percentile score of 1,480 was reported as 1,510.