While most students were sleeping off Harvard-Yale hangovers two weeks ago, University President Lawrence H. Summers was toasting his middle age amid the company of family, friends and dinosaur skeletons at the Harvard Museum of Natural History.

Summers turns 50 today, but he kicked off celebrations a few weeks early with an invitation-only fete—replete with champagne and chocolate birthday cake—for close friends and family the Saturday night of Harvard-Yale weekend.

Guests dined on chicken and pasta, wined on the open bar, and toasted to five decades of Larry. Two of Summers’ former colleagues from his Treasury days in Washington gave a powerpoint presentation detailing “What it’s like to work for Larry,” and his brother toasted him with a soliloquy: “To Drink or Not Drink Diet Coke.”

“It was a wonderful time,” said Anita Summers, Larry’s mother, adding that the museum was a unique venue, allowing the guests to “stroll among all the exhibits.”

It might have been a family-oriented party, but the crowd was young, hip, and kept the party raging well after the clock struck twelve. Anita confirmed yesterday that she and Larry’s father, Robert, were the oldest guests in attendance.

The A-list also included Larry’s brothers, John and Richard Summers ’79; his three children, Pam, Ruth and Harry; his long-time girlfriend, English Professor Elisa New; and members of his former staff in the Clinton Treasury Department.

The Callbacks, a campus a capella group, and members of the Gilbert and Sullivan players, a theatre troupe, provided the evening’s entertainment.

George H. Blaustein, a graduate student in English who is close to New, played the piano during the cocktail hour. “I concentrated on playing, and therefore didn’t really notice any notable deans, professors and politicos,” Blaustein said. “Other festivities were lined up after cocktails and dinner, but unfortunately I was unable to stay for very long.”

The Callbacks, who also performed at New’s daughter’s Bat Mitzvah last spring, sang three songs, all of which were punctuated by personal speeches and toasts from friends of Summers. They began with “Sunday Morning,” a popular song by Maroon 5, then sang a new take on a classic, “Ain’t No Sunshine (When He’s Gone),” and finally, “Happy Birthday.”

“It was amusing because we rehearsed singing ‘Happy Birthday President Sum-mers’ so much since it is a tough name to sing,” said Kieran H. Shanahan ’07, a member of the group. She added that The Callbacks prepared a lot for the performance—despite its proximity to the Harvard-Yale game—but that the hard work paid off.

“It was a really big honor because you knew there were very distinguished guests in the audience,” Shanahan said. Though the crowd was full of VIPs, she said, they were “loosened up, really in a festive mood” when the Callbacks arrived at 9:30 p.m. “The only awkward thing,” she said, “was that...right behind where we were singing and people were giving speeches there was this enormous, 50-foot long dinosaur skeleton.”

Nonetheless, Shanahan said that she and the group got “a kick” out of seeing their President’s childhood friends and hearing anecdotes of his younger days.

FIVE DECADES OF LARRY

Summers was born to a family of economists in New Haven, Conn., on Nov. 30, 1954. He grew up in a suburb of Philadelphia, and attended public schools while his parents taught economics at the University of Pennsylvania.

His mother Anita said yesterday that from his first moments, Larry always put up a fight.

“Even when he was three years old, you would say something to him and no matter what, he would respond with ‘No!’ and then he would argue,” she said. “It would drive you crazy, but this was his way of learning.”

“When he was a teenager, this became more difficult,” she added. “It was his form of testing boundaries.”

The 18-year-old Summers soon shipped off to the Massachusetts Institute of Technology (MIT). He received his bachelor’s degree in 1975, and moved five minutes down the road to begin his Harvard career as a graduate student in economics, landing spots as a tutor in Lowell House and teaching fellow in Ec 10. Before finishing his dissertation, he began teaching economics as an assistant professor at MIT.

At 28, Summers finished his dissertation, “An Asset-Price Approach to Capital Income Taxation,” and Harvard awarded him a Ph.D. in 1982. After three years as assistant professor at MIT, he spent one year as an associate professor before heading to Washington to become a domestic policy economist for the President’s Council of Economic Advisers.

In 1983, at age 28, he returned to Harvard to become one of the youngest tenured professors in University history.

Four years later, Summers received a chair and served as the editor of a prominent economic journal, the Quarterly Journal of Economics.

In 1991, Summers left for Washington again to become the chief economist of the World Bank, a job that led him to help bail Mexico out of its 1995 financial crisis.

In the same year, Summers became deputy to U.S. Treasury Secretary Robert E. Rubin ’60, whose position Summers would himself assume four years later under President Bill Clinton.

“Whether it was the world bank or the treasury he always talked about the big objectives,” Anita Summers said. “The smaller things took on more meaning and content because they are tied to a bigger thing.”

In 2001 the Harvard Corporation appointed Summers the 27th president of Harvard. During his tenure, Summers has spoken about anti-semitism in higher education, began planning for a major science campus in the Allston neighborhood of Boston and advocating tenuring younger faculty at Harvard.

One faculty member who was not invited to the soiree questioned how Summers’ aging process might affect his views on faculty hiring.

“Of course the real question is: Is Larry now beyond the age where his best work is ahead of him, as he is fond of saying in testing faculty appointments?” the faculty member said.

During his tenure at Harvard he has drawn national attention for his combative nature and aggressive leadership style—traits his mother said she sees emerging in the next generation.

“Some of his children are acquiring the same talent,” she quipped.

Summers may be over the hill, but he seems to be enjoying the view. “So far, 50 is easier than 40,” he said yesterday. “When I turned 40, I couldn’t feel young anymore.” Now, he said, he no longer has that problem.

—Staff writer Lauren A. E. Schuker can be reached at schuker@fas.harvard.edu.