CAMBRIDGE, Mass., June 5 — Speaking on Harvard's 352nd commencement day, Lawrence H. Summers, the university's president, pledged today to reshape the undergraduate experience, including the core curriculum.

Beneath an ashen sky, Mr. Summers spoke proudly of Harvard's many strengths but also said that undergraduate students craved more contact with senior faculty members and that improvement was needed in the mentoring system.

Of the first overhaul of the curriculum in 30 years, he said, "No organization, and certainly not one as creative as Harvard College, should ever go more than a generation without reassessment and renewal."

The college has disclosed few details of the curricular overhaul, which will be a subject of prolonged study.

Ernesto Zedillo, former president of Mexico, who received an honorary doctor of laws degree, used his speech to praise the United States for leading the creation of international institutions in the first half of the 20th century. But he also cautioned Washington against acting unilaterally and abusing its position as the world's sole superpower.

"All the nations on earth, even the most powerful one, need the multilateral system," he said.

In accordance with Harvard tradition, the speeches by Mr. Summers and Mr. Zedillo were given at the Harvard Alumni Association's annual meeting, which followed a ceremony this morning to award degrees. In all, 6,349 degrees were conferred, 1,586 of them to graduates of Harvard College.

At this morning's ceremony, which drew a crowd estimated at 30,000, each group of graduates carried its own prop as degrees were awarded collectively. The business school students waved cash in the air. The law school graduates pumped fists clutching inflatable sharks. Medical school graduates tossed surgical masks in the air, while the graduates of the Kennedy School of Government waved plastic beach balls imprinted with the map of the globe. Divinity school graduates had gold halos attached to their mortarboards.

The ceremony opened with a call to order by the sheriff of Middlesex County, and the first speech was a salutatory address given in Latin by Charles B. Watson Jr.

"Now after reading through innumerable books, after writing endless papers, finally, we have arrived at this day on which, finally relieved from all your cares, you get to hear me speaking in Latin," Mr. Watson told his classmates, according to a translation provided in the program.

In addition to Mr. Zedillo, there were 10 other honorary-degree recipients: Gary S. Becker, winner of the 1992 Nobel Memorial Prize in Economic Science; Elliot Forbes, emeritus professor of music at Harvard; Norman C. Francis, president of Xavier University in New Orleans; Ellsworth Kelly, painter and sculptor; Mary-Claire King, geneticist; Donald E. Knuth, computer programming pioneer; Linda Nochlin, art historian; Philip Roth, the novelist; Robert G. Stone Jr., longtime Harvard trustee and fund-raiser; and P. Roy Vagelos, former chief executive of Merck & Company.