But by the time Michael R. Bloomberg left Johns Hopkins University, with a smattering of A's and a lust for leadership, he was a social and political star — the president of his fraternity, his senior class and the council overseeing Greek life. "An all-around big man on campus," as he puts it.
His gratitude toward the university, starting with a $5 donation the year after he graduated, has since taken on a supersize, Bloombergian scale.
On Sunday, as he makes a $350 million gift to his alma mater — by far the largest in its history — the New York City mayor, along with the president of the university, will disclose the staggering sum of his donations to Johns Hopkins over the past four decades: $1.1 billion.
That figure, kept quiet even as it transformed every corner of the university, makes Mr. Bloomberg the most generous living donor to any education institution in the United States, according to university officials and philanthropic tallies.
The timing of his latest donation, as the mayor's third term draws to a close, offers a glimpse of the sky-is-the-limit philanthropy that he and his aides say is likely to dominate his life after City Hall. The mayor, who is 70, has pledged to give away all of his $25 billion fortune before he dies, and he has built up a foundation on the Upper East Side of Manhattan to carry out the task.
At the same time, the donations highlight the unusually close relationship between Mr. Bloomberg and Johns Hopkins, which, interviews show, has played an unseen role in several of his biggest undertakings as mayor.
In an interview here, Mr. Bloomberg said he was making his donations public to encourage greater charitable giving toward education. He lamented, "In our society, we are defunding education."
The mayor, a member of the class of 1964, explained his fidelity to the university in deeply personal terms. Johns Hopkins, he said, was where he escaped the crushing boredom of Medford High and discovered an urban campus of stately Georgian buildings brimming with new people and ideas.
"I just thought I'd died and gone to heaven," he said.
"If I had been the son of academics," he added, "maybe I would have been on campuses and would never have been as impressed as I was when I was here, because it's the first time I really was walking among people who were world leaders, who were creating, inventing."
Johns Hopkins as it exists today is inconceivable without Mr. Bloomberg, whose giving has fueled major improvements in the university's reputation and rankings, its competitiveness for faculty and students, and the appearance of its campus.
His wealth — not to mention a small army of his favored architects, art consultants and landscape designers — has bankrolled and molded the handsome brick-and-marble walkways, lamps and benches that dot the campus; has constructed a physics building, a school of public health, a children's hospital, a stem-cell research institute, a malaria institute and a library wing; has commissioned giant art installations by Kendall Buster, Mark Dion and Robert Israel; and has financed 20 percent of all need-based financial aid grants to undergraduates over the past few years. (Even his ex-wife and in-laws make a campus cameo, on the dedication plaque for a science building he financed.)
"The modern story of Hopkins is inextricably linked to him," said Ronald J. Daniels, the university's president, as he walked around the campus recently. "When you look at these great investments that have transformed American higher education, it's Rockefeller, it's Carnegie, it's Mellon, it's Stanford — and it's Bloomberg."
Hopkins, in return, has become something of a brain trust for Mr. Bloomberg, shaping his approach to issues like cigarette smoking, gun violence and obesity.
It was faculty members at Hopkins who introduced Mr. Bloomberg, as a donor and as a trustee, to a growing body of science linking behavior and disease.
"That is when he discovered public health," said Alfred Sommer, the dean of the Johns Hopkins Bloomberg School of Public Health from 1990 until 2005.
At times, Mr. Bloomberg, then a high-flying entrepreneur, was resistant to paying for such research, arguing that some of the most intractable health problems were best left to government. "That's policy; that's politics," Mr. Sommer recalled him saying.
But the underlying ideas stuck, and, as mayor, Mr. Bloomberg pressed the City Council to ban smoking in city parks, and the Board of Health to require fast-food chains to post calorie counts and restaurants to stop selling oversize sodas.
"He was in a position to act on things he had once told us we really shouldn't be bothered with," Mr. Sommer said. "He has been the public health mayor ever since."
Years before he would banish cars from parts of Times Square, Mr. Bloomberg removed them from the quads of Johns Hopkins as chairman of the board of trustees, arguing they were unsightly and impeded socializing. (To hide them, he paid for an underground parking garage.)
The relationship between Mr. Bloomberg and Hopkins is, much like the college admissions process, the product of happenstance.
In high school, Mr. Bloomberg worked at an electronics company whose owner happened to have a doctorate from the university. She urged him to apply, despite his mediocre transcript.
"Let's be serious — they took a chance on me," Mr. Bloomberg said.
At Hopkins, the boyish-looking Mr. Bloomberg, whose high school classmates branded him "argumentative" in a class book, blossomed into a charismatic figure, eager to organize those around him. An engineering major, he persuaded his fraternity brothers to pay for a chef to replace a chaotic dinnertime routine, and he doled out assignments to lab mates. "He was like the project manager, at 19 years old," Jim Kelly, a classmate, said.
On campus, Mr. Bloomberg discovered the addictive power of the limelight. When a local judge, tired of hearing cases involving misbehaving Hopkins fraternity brothers, called for an end to Greek life at the college, Mr. Bloomberg challenged him to an hourlong public debate. A healthy crowd showed up for the occasion.
"Mike not only held his own," Mr. Kelly recalled, "he beat him."
Mr. Bloomberg still relishes his star turn in campus governance. "It's the first time that I ever headed something," he said. "The first time I got a chance to pull people together."
These days, his status as the university's top donor has given him mayorlike sway at Hopkins: deans routinely travel to New York to pitch him new programs and research.
His latest passion: genetically engineering mosquitoes to prevent the transmission of malaria. "He always asks about the mosquitoes," said Dr. Peter Agre, a Nobel Prize-winning professor at the university, where Mr. Bloomberg has paid for a temperature-controlled center to cultivate the bugs. The mayor of New York City now speaks of "building a better mosquito."
Mr. Bloomberg tends to finance ideas that appeal to his contrarian style and corporate ethos. For years he has rotated top executives around his media company to encourage collaboration. In the hope of replicating that experience, most of his latest donation, about $250 million, will be used to hire 50 new faculty members who will hold appointments in two departments as they pursue research in areas like the global water supply and the future of American cities. (The remaining $100 million will be devoted to financial aid.)
His approach to philanthropy at the university is remarkablyhands-on. A trusted mayoral architectural adviser, Allen Kolkowitz, and an art guru, Nancy Rosen, guided the construction of the new Charlotte R. Bloomberg children's hospital, named for the mayor's mother. The building's colorful exterior is a whimsical take on Monet's paintings at Giverny. "He got very involved in the design," said Dr. Edward D. Miller, the former chief executive of Hopkins Medicine.
Of course, certain courtesies are extended to a donor at Mr. Bloomberg's level. When Dr. Miller realized that the Charlotte R. Bloomberg Children's Center would be connected to a new tower named for Sheik Zayed bin Sultan al-Nahayan, the former president of the United Arab Emirates, he nervously called the mayor.
"Will you have a problem with this?" he asked Mr. Bloomberg.
The mayor thanked him for the call, but made clear he had no objection. "A Jew on one side, an Arab on the other," he told Dr. Miller. "That's what we should do in this world."