On an idyllic spring evening, in a stately quadrangle framed by red-brick buildings with white pillars, former U.S. Senate Majority Leader Bill Frist delivered the commencement address to the 2007 graduating class of Montgomery Bell Academy, an aristocratic prep school in Nashville. Founded in 1867, Montgomery Bell is the South’s oldest boys school; it aims to develop each of its 700 students into a “gentleman, scholar, athlete.” Alumnus Tom Schulman, who won an Oscar for his screenplay for Dead Poets Society, modeled the hidebound school in that 1989 film on Montgomery Bell and the Robin Williams character on an inspirational teacher there.

A 1970 graduate to whom a campus monument is dedicated, Frist reminded the crowd that his family’s connection to the elite institution spans three generations. His late father, Thomas Frist, was personal physician to five Tennessee governors and served on the academy’s board for more than four decades. “He sat where you parents sit today on seven occasions, for three sons and four grandsons,” Bill Frist said.

Over the years, the Frists have donated handsomely to Montgomery Bell, which named its dining hall for the family. Bill, who joined the school’s board last year, has given at least $1 million. But an even bigger supporter has been Bill’s oldest brother, Tommy Frist, the 70-year-old billionaire co-founder of Hospital Corporation of America, the nation’s largest for-profit hospital chain. Tommy is a legend at Montgomery Bell, where he was a star quarterback on a state-championship football team. Graduating in 1956, he joined M.B.A.’s board in 1971, donated at least $5 million, and sent both of his sons there.

Unmentioned during Bill’s commencement speech was Tommy’s dramatic break with M.B.A. after a failed, never-before-reported philanthropic power play. In 2001, he had offered Montgomery Bell at least $100 million—a record amount at the time—on one condition: Tommy, who has seven granddaughters under the age of 15, stipulated that the school would have to admit girls. The board rejected his offer.

But Tommy didn’t just walk away. After quitting the board, he financed the construction of a new coed high school and campus, an extension of the elementary and middle school that for years had sent most of its male eighth-grade graduates to Montgomery Bell. Thus, in one stroke, Tommy not only created an instant rival to his alma mater but also deprived it of its biggest source of students. Other tycoons have famously balked when recipients didn’t comply with their terms or offended them in other ways. Texas billionaire Lee Bass withdrew a $20 million gift to Yale for Western-civilization studies after some faculty members urged that the money be spent on multicultural curriculums.

Nike founder Phil Knight suspended payments on his $30 million gift to the University of Oregon until the school backed away from criticizing the company’s overseas labor practices. But Tommy has taken this type of controlling approach even further; his strong-arm tactics are reminiscent of fierce corporate struggles in which a spurned executive exacts revenge by luring away employees and siphoning off promising new talent.

The new Ensworth High, which opened in 2004 and graduated its first class in May, immediately began poaching Montgomery Bell’s faculty. It even paid a six-figure salary to snare Montgomery Bell’s state-championship-winning football coach—no small triumph in a state that matches Texas’ passion for teenage football games under Friday-night lights. In October 2007, when the schools clashed on the gridiron for the first time before an overflow crowd in Montgomery Bell’s stadium, Tommy—who had paid for the statue of his former coach that stands near the main gate—shed his longtime allegiance and took his seat on the visitors’ side of the field.

“It’s widely said in Nashville that there are three ways to do things,” says one longtime observer of local philanthropy. “The right way, the wrong way, and the Frist way—‘Do what I tell you or I’ll take my marbles and go home.’”

The street signs in the affluent Nashville suburb of Belle Meade are topped with wrought-iron mare-and-colt sculptures, a reference to the horse corrals lining the vast lawns of its stately mansions. Tommy and Bill Frist own homes there, as does Al Gore. For many Belle Meade families, the choice between Montgomery Bell and Ensworth High has become as defining as which church they worship at or which Republican they vote for. As they drive down Belle Meade Boulevard on weekday mornings, they turn right on Harding Road to go to M.B.A. or left to go to Ensworth High.

Those who turn left eventually arrive at a 127-acre hilltop campus that was once a Civil War-era plantation. Ensworth features the latest in educational fads and furnishings. Its freshmen study a mix of physics, biology, and chemistry, instead of focusing on just one of the three, as at most schools. For the dramatically inclined, a 665-seat performing-arts theater is under construction. Each of Ensworth’s 400 students is provided with not only a laptop computer but also a personalized fitness program; they pump up in a 10,000-square-foot weight room larger than that of Nashville’s N.F.L. team, the Tennessee Titans. “It’s like a school on steroids,” says the father of a prospective student.

In Founders Hall, a display lists the school’s principal backers. The first eight names: Tommy and Trish Frist, their three children, and their children’s spouses. Tommy and his wife funded the lead gift, about $35 million, from their personal fortune. Their daughter, Trisha Elcan, and her husband, Charles, donated the land, which they had purchased for $4 million.

The family made sure that its investment was well spent. Tommy and Trisha kept close tabs on construction, visiting the site regularly, says project architect John Prokos. “He wanted Ensworth to have its own unique identity”—different from Montgomery Bell’s. Tommy and Trisha toured other new prep schools, alongside Ensworth administrators seeking guidance. The night before Ensworth High opened, Trisha took a broom and swept up rubble in the halls.

Montgomery Bell’s students and faculty watched the newcomer warily. Kevin Seitz, who graduated from M.B.A. in 2006 and attends Harvard, says he and his teammates on the cross-country team used to detour from their normal practice route to run past the Ensworth campus and marvel at it. “They have so much land over there,” he says. “That’s one thing we were jealous of.”

Ed Caudill, a former Montgomery Bell math teacher who joined Ensworth’s staff and has sent his three children to the school, says the relationship between the two institutions is “more competitive than I think it should be. It’s brother against brother.”

The Frist dynasty’s contribution to Nashville is hard to overlook, because it’s branded on three of the city’s premier tourist attractions. The ­Country Music Hall of Fame boasts a Frist Library and Archive, while the Cheekwood Botanical Garden and Museum of Art features a Frist Learning Center. The crown jewel is the Frist Center for Visual Arts in downtown Nashville, where even the parking-lot traffic cones are labeled frist.

Few in Nashville begrudge this self-promotion. Here, the Frists are widely heralded as health-care visionaries who helped diversify the city’s economy beyond banking and insurance. H.C.A., where Tommy served as chief executive from 1987 to 1994 and again from 1997 to 2001, remains Nashville’s largest corporate employer and has spun off some 25 publicly traded health-care companies in the region. Tommy successfully lobbied pharmacy-benefits management firm Caremark to relocate to the city in 2003. Other businesses that have subsequently shifted operations to Nashville include Nissan Motor and building-products supplier Louisiana-Pacific.

An Air Force flight surgeon during the Vietnam War, Tommy co-founded H.C.A. in 1968 with his father and Jack Massey. In 2006, when Tommy, Bain Capital, Kohlberg Kravis, and Merrill Lynch took H.C.A. private in a $33 billion leveraged buyout, he sold back 16 million shares valued at $892 million.

Tommy still chairs H.C.A.’s former foundation, which was renamed the Frist Foundation in 1997 and supports an array of Nashville nonprofits. For the most part, the foundation isn’t giving away Tommy’s own fortune; it derives most of its $210 million in assets from company stock options that it cashed out. In recent years, it has scaled back funding for some causes to subsidize the Frist Center for the Visual Arts.

Organizations that ignore Tommy’s views about how his money should be spent do so at their financial peril. Several years before he walked away from Montgomery Bell, he had discussed a multimillion-dollar gift with another Nashville institution, Vanderbilt University, where he had earned a bachelor’s degree in 1961 and where he served as a trustee. As was the case with Montgomery Bell, the offer came with strings attached. Tommy, who planned to donate H.C.A. stock, wanted the right to decide when the university would sell the shares. Vanderbilt prohibits such a restriction, and Tommy never made the gift. The chancellor at the time, Joe Wyatt, says the university would not have waived the rule because, since Tommy was a trustee, a waiver would have appeared to favor an insider.

The final break came when Vanderbilt chairman Bronson Ingram died in 1995. As vice president of the board and its richest member, Tommy was viewed by many as Ingram’s likely successor. But several trustees opposed his appointment, saying it would create a conflict of interest: Tommy’s company, H.C.A., owns nine hospitals in the Nashville area that compete with Vanderbilt University Medical Center for patients, and Tommy had once broached the possibility of H.C.A. buying Vanderbilt’s hospital. After Vanderbilt signaled that Tommy wouldn’t be named to the chairmanship, he announced that he wasn’t a candidate. “My sense was, when Tommy didn’t get the spot, he went away mad,” says a former Vanderbilt administrator. In September 1997, Tommy resigned from Vanderbilt’s board.

A month later, he and other family members gave $25 million to one of Vanderbilt’s top competitors for Southern students: Princeton University. Tommy’s two sons and his brother Bill had gone to Princeton, but Tommy had never studied there. Soon, Princeton renovated a physics building into the Frist Campus Center. A person familiar with the university’s fundraising says that Tommy still contributes modestly to Vanderbilt athletics and its nursing school (which has a wing named after Tommy’s wife), but the university is “definitely off his list” for major donations. Around campus, according to another insider, Princeton’s windfall is remembered as the “Fuck you, Vanderbilt” gift.

One alma mater down, one to go. Tommy’s overture to Montgomery Bell came in late 2001 when he approached the executive committee of its board with his stunning nine-figure offer. At the time, no one had ever given such a large gift to a U.S. prep school. The biggest single donation ever to Montgomery Bell had been about $10 million, and the school’s assets then totaled $69 million.

But Montgomery Bell would receive the prize only by merging with its longtime feeder school, Ensworth, to create a coeducational K–12 school. Founded in 1958, at a time when court-ordered desegregation of public schools prompted many white families to seek private education, Ensworth’s lower school teaches boys and girls through eighth grade on a Tudor-style campus (which includes—what else?—Frist Hall) only a quarter-mile from Montgomery Bell. If Montgomery Bell refused, Tommy indicated, he would build a high school for Ensworth.

In a statement provided by an H.C.A. spokesperson, Tommy says, “The establishment of a coeducational secondary school was of particular interest to me, as I have long believed in the importance of parity in education for our young men and women.” According to a friend, Tommy regards single-gender schools as relics of an era when Southern girls weren’t supposed to go to college or have careers. Tommy’s daughter, Trisha, has said that when she graduated from eighth grade in 1979, she felt her only option was Nashville’s elite private high school for girls, Harpeth Hall (best known as actress Reese Witherspoon’s alma mater). Around that time, Tommy encouraged Harpeth and Montgomery Bell to merge. Both schools balked.

Nashville does boast another premier private coed K–12 institution, University School. But it may clash with the Frists’ style. University School caters to the city’s intellectual, rather than social, elite. Its high school doesn’t have a football team. Parents, many of whom belong to Vanderbilt’s faculty or staff, lean politically liberal and Democratic. One is likely to see a Prius with an Obama sticker in the carpool line at University School, versus a Suburban with a McCain decal at Montgomery Bell or Ensworth; McCain held a campaign rally at M.B.A. last February. Montgomery Bell has an indoor rifle range; University School has a Gay-Straight Alliance.

When Trisha and her brothers began having daughters, Tommy resumed his campaign for a coeducational prep school. Trisha has three daughters at Ensworth, the eldest in eighth grade. “I’ve heard people associated with M.B.A. say, ‘If Trisha had three sons, this never would have come up,’ ” says an Ensworth insider.

Montgomery Bell’s executive committee referred Tommy’s proposal to the full board, which also included his younger sister Mary Louise’s husband. After much behind-the-scenes ferment, the board rejected the offer without even taking a vote. The consensus was that an all-boys school was both central to Montgomery Bell’s identity and an educational approach still sought by many Nashville parents.

Daniel McGugin, then assistant football coach at Montgomery Bell and now head coach, was privy to the board’s discussions because his father was an M.B.A. trustee. M.B.A. turned down the offer, he says, because educating boys “is who we are, what we do.” Tommy’s vision was “a pretty fundamental difference.”

Despite the outcome, M.B.A. headmaster Brad Gioia says he remains fond of Tommy: “I miss seeing him around.”

Tommy Frist and his family provided two of the prerequisites for opening a new prep school: money and land. But there was one they couldn’t buy: top students. Montgomery Bell and the girls academy, Harpeth Hall, had for years tapped Ensworth lower school’s best graduates. Now, like any retailer competing for customers in a niche market, Ensworth administrators embarked on a hard-sell campaign to keep its students from moving elsewhere.

As a flute-playing Ensworth eighth-grader in 2004, Mary Julia Bressman feared that the new high school would cater more to athletes than to arts-oriented students; after all, its first high-profile hire was M.B.A.’s championship football coach. Ensworth administrators pressured her to enroll in the new school. “They’d call our house—‘Maybe there’s something we can do to change your mind?’ ” says Bressman, who held her ground and enrolled at Harpeth Hall. “For a 14-year-old, it was a little difficult to deal with. It put a lot of stress on me.”

The lobbying was “relational” rather than high-pressure, says David Pack, Ens­worth High’s former dean of students. “We knew those kids. The high school was designed with them in mind.”

Alex Peerman, an Ensworth eighth-grader in 2004, says school administrators “gave us the full-court press.” One day, they took Peerman and his classmates to the construction site, where the students ate ice cream while hearing a pitch from the chair of the science department. Demonstrating how materials change properties at low temperatures, the teacher froze a Ping-Pong ball in liquid nitrogen; when he threw it against a wall, it shattered, delighting the teenagers.

Peerman chose Ensworth High. “It’s a coed world, and you should grow up in a coed world,” he says. Peerman proved to be a good get for the new school. As a member of the inaugural class, he helped write the student-government constitution, edited the school newspaper, and was captain of the soccer team. A National Merit Scholar, Peerman now attends Princeton.

Ensworth pushed particularly hard to keep top jocks like promising runner Christian Waddey. Soon after Montgomery Bell’s football coach defected in 2002, he pitched Ensworth High to Waddey’s parents, but the youth had made up his mind to transfer to M.B.A. “We don’t like Ensworth at all,” says Waddey, who now attends the University of Virginia. “They’re trying to imitate M.B.A. and beat M.B.A.”

Sometimes those who left Ensworth felt their ex-classmates’ wrath. Cate Tidwell, like Bressman, opted for Harpeth Hall in 2004. When her freshman soccer team played Ensworth for the first time, she walked over to say hi to her friends on the Ensworth side. “They all started chanting ‘traitor’ to me,” she says. “I had to leave. That brought me to tears.”

Since then, Ensworth High has demonstrated its staying power, succeeding in re-enrolling more than 80 percent of its lower-school eighth-graders. Meanwhile, the rivalry between the two schools has only intensified. At Montgomery Bell, which has seven National Merit semifinalists this year, compared with six for Ensworth, students tend to scoff at its upstart challenger. During an assembly in February, a member of the school’s championship mock-trial team announced that it had vanquished St. Cecilia’s Academy, Father Ryan High School, “and, of course, Ensworth.”

Frist partisans maintain that establishing a coeducational prep school made sense for the city and local business. They say that Ensworth High, strategically located in the heart of Nashville’s fast-growing wealthy suburbs, is an asset for H.C.A. and other firms in recruiting executives leery of sending their children either to Nashville’s struggling public schools or to single-gender private schools.

But Montgomery Bell stalwarts continue to take pride in the fact that its identity was not for sale, even to a favorite son like Tommy Frist. “The whole notion that an enormous sum of money could establish that same prestige and success” that Montgomery Bell enjoyed as an all-boys school “was kind of puzzling,” says 2006 graduate Kevin Seitz. “It made you think, ‘What can money buy?’ ”

Donations to America’s elite private schools have been swelling in recent years. here are some of the biggest contributions.

1. The George School
Newton, Pennsylvania
Amount: $128 million
Donor: Barbara Dodd Anderson
Year: 2007

2. Lakeside School
Seattle
Amount: $40 million
Donor: Bill and Melinda Gates Foundation
Year: 2005 

3. Fork Union ­Military Academy
Fork Union, Virginia
Amount: $60 million
Donor: Guy and Betty Beatty
Year: 2002

4. Phillips Exeter Academy
Exeter, New Hampshire
Amount: $25 million
Donor: Anonymous
Year: 2005

5. Culver Academies
Culver, Indiana
Amount: $20.8 million
Donor: Frank and Jane Batten
Year: 2003

6 . Mercersburg Academy
Mercersburg, Pennsylvania
Amount: $35 million
Donor: Gerry and Marguerite Lendfest
Year: 2000

7. Phillips Academy
Andover, Massachusetts
Amount: $25 million
Donor: Oscar L. Tang
Year: 2008

8. Woodberry Forest School
Woodberry Forest, Virginia
Amount: $25 million
Donor: The estate
of Randall Terry Jr.
Year: 2006