Dean of the College Benedict H. Gross '71 announced on Wednesday that he will step down August 31, saying it was his own choice to resign.

"This was entirely my decision—I just felt that five years was enough!" he said in an e-mailed statement to The Crimson. "You can take the Magic of Numbers from me in the fall," Gross added, suggesting that he plans to stay at Harvard and continue the popular Quantitative Reasoning course he has taught in the past.

A statement from the Faculty of Arts and Sciences said Gross had decided that "with the conclusion of the legislative process of the curricular review, the time seems appropriate to move on to other projects." Gross, in a letter to Interim Dean of the Faculty David Pilbeam, said that "this summer marks the end of my five-year administrative appointment."

Throughout the spring, however, Gross, 56, gave no indication of planning to resign. He said, for instance, that he was considering launching a review of the College's Administrative Board in the fall. (Gross today reiterated his support for Ad Board reform, saying he would suggest it to the next dean.)

Pilbeam said in a phone interview that Gross's resignation is "a decision that he is very comfortable with."

"He is ready for the next challenge, whatever that is," Pilbeam said.

Computer scientist Michael D. Smith, who will take over as dean of the Faculty of Arts and Sciences July 15, will pick Gross's successor. Gross said he expected Smith to make the choice after coming back from vacation next month.

Smith, who is in Europe with his family, did not respond to a request for comment.

But in a letter sent to Faculty members on Wednesday, Smith solicited suggestions from professors to assist in the selection of a new dean.

"I welcome your advice about the current strengths and challenges of the College, as well as your nominations of colleagues who would be especially well-suited to lead the College beginning this fall," he wrote.

Gross, a prominent mathematician, has served as dean of the College since July 2003, when the positions of dean of the College and dean of undergraduate education were consolidated. He was the dean of undergraduate education in 2002-2003.

After nearly five years of debate, the Faculty approved a new program of general education last month that will replace the generation-old Core Curriculum. The program may go into effect as early as fall 2008, and the dean of the College will be key to ensuring that the transition goes smoothly.

In the Faculty's news release, Interim President Derek C. Bok praised Gross for his contributions to student life.

Under Gross, the College undertook high-profile initiatives to boost Harvard's standing as a school with a less-than-satisfactory social life. The past year saw the opening of several new College-funded social spaces, including the Lamont Library Café and a campus pub.

—Samuel P. Jacobs contributed to the reporting of this story.

—Staff writer Brittney L. Moraski can be reached at bmoraski@fas.harvard.edu.