Jerome Kohlberg Jr., the private equity industry visionary who became one of Wall Street’s biggest critics, quiet philanthropist, family man and nimble third baseman on the Chilmark softball field, died July 30 at his home on Job’s Neck cove in Edgartown, surrounded by his family. Mr. Kohlberg, who was 90, had battled cancer for a number of years, attacking his illness the same way he lived his life, with toughness, piercing intelligence and sheer willpower.

He and his wife Nancy bought the Gazette nearly five years ago, marking a new chapter in the 164-year-old newspaper of record for the Island and continuing its ownership as a family-held, independent publishing entity. “My goal is to give back to the Vineyard and to the Gazette,” he said at the time.

Jerome Kohlberg bought the Gazette in 2010. — Mark Lovewell

In a lifetime of accomplishments, he believed above all in doing the right thing. “To thine own self be true — I feel like I’ve heard Dad say it a hundred times,” his daughter Karen Kohlberg Davis said. Daughter Pamela Kohlberg added, “He felt moral issues came into everything.”

He had summered on the Vineyard since the 1940s, first in Chilmark and later in Edgartown. David Flanders helped the Kohlbergs find their first piece of land in Chilmark and Emmett Carroll built them a house. Many years later he and Nancy bought part of what was formerly Pohogonot Farm and built their current home on a tranquil cove of the Edgartown Great Pond.

Jerome Spiegel Kohlberg Jr. was born on July 10, 1925, and grew up in New Rochelle, N.Y., a member of the generation whose outlook was shaped by the Depression. His father was in the import/export business, and his mother was a writer and charity worker who had a profound influence on him. “She, even more than my father, imbued in my brother and me a sense of values and ethics,” he said in an autobiography. “She stressed the importance of standing up for what is right.”

He was educated in public schools and later enrolled at Swarthmore College, where he was a popular student and competitive athlete. He was inspired by the college’s Quaker philosophy; many years later when he joined the Swarthmore board of trustees he described himself as the college’s first Jewish Quaker.

In 1943, he joined the Navy, serving in Panama as a supply officer. After the war he used the GI Bill to attend Harvard Business and Columbia Law schools, and later fought to ensure veterans continued to receive education benefits. He married Nancy Seiffer in 1948; they had four children: Karen, Pam, Jim and Andy. After law school he clerked in Portland, Ore., for Gus Solomon, a federal district court judge who became a lifelong role model. In 1955 he left the law and headed for Wall Street.

He spent 21 years at Bear Stearns, along the way developing a strong set of creative innovation skills in finance. “I had a dream that companies could be bought and investments made in undervalued businesses,” he told his friend Peter Kunhardt, who conducted an oral history with him, “where we as financiers would invest our own money, time and effort right along side the others and stand or fall on that. I loved the business of buying companies and helping them prosper.”

In 1976 he founded Kohlberg, Kravis, Roberts and Co., partnering with Henry Kravis and George Roberts, two younger cousins who had begun their careers under his mentorship. He put up his own money to start the company and agreed to guarantee the salaries of his partners given the risk involved.

Mr. Kohlberg in the Gazette newsroom just after Jane Seagrave was hired as publisher in 2011. — Mark Lovewell

K.K.R. became known worldwide, and the leveraged buyout revolutionized the financial investment industry.

In 1983 Mr. Kohlberg was diagnosed with acoustic neuroma, a type of brain tumor. Following surgery and a year of recovery, he returned to K.K.R. where he found the culture had changed for the worse. “His signature down-to-earth style and sense of fairness had been replaced with fast-paced hostile takeovers that included extra fees to enrich K.K.R. His whole philosophy of business, and life, was being challenged,” wrote Mr. Kunhardt.

The threshold moment was chronicled in the book Barbarians at the Gate by Bryan Burrough and John Helyar about the fall of RJR Nabisco:

“The gap between Kohlberg and Kravis was widened by the stark difference in their lifestyles. Kohlberg was a homebody, married to the same woman for forty years. Money hadn’t changed him. He dressed simply, led a quiet family life, and spent his free time playing tennis or reading thick volumes of fiction or biography. His idea of entertaining was tossing a softball around on a Sunday afternoon and retiring early to read.”

In March 1987, Mr. Kohlberg left the company he had founded, stunning Wall Street with a final boardroom speech where he said in part: “We must all insist on ethical behavior or we will kill the golden goose.”

He went on to found an independent investment company with his son James, retiring in 1994. He continued a wide array of philanthropic pursuits, from the corridors of Washington D.C. where he championed campaign finance reform, to the Vineyard where he backed education, conservation and sustainable farming initiatives.

A regular at Chilmark softball, Jerry Kohlberg loved the "hot corner" at third. — Peter Simon

A lifelong athlete, he was a legendary figure at Chilmark Sunday softball, known for his skills at third as well as at the plate. “I played third up until I got too old, then I went to short, then to second as my arm gave out, but that took 50 years” he told former Gazette managing editor Lauren Martin in a 2010 personal interview as he was preparing to buy the newspaper.

Adam Wilson, an Oak Bluffs resident and the Aquinnah town administrator, recalled the early years of softball at Toomey’s field in a comment published on the Gazette website this week. “Jerry loved playing third, the ‘hot’ corner,” Mr. Wilson wrote. “He had a floppy hat and wore granny glasses and always vowed that no ground ball would get past him (And none ever did). Arguments would always break out about players beating the throw to first or how far the mythical foul line went toward the house and driveway. Some of the arguments were quite heated. But Jerry was always viewed as being the wisest among us and his pleading to end an argument with, can we just play ball, would rule the day.

“I think if you went back to Toomey’s, you’d find Jerry standing there, glove, hat, glasses and all, just waiting for someone to hit him a ground ball.” Although few of the regulars knew, Jerry Kohlberg was the reason the field later got a fence and other improvements.

He and Nancy lived in Edgartown and at Cabbage Hill Farm in Mt. Kisco, N.Y. They bought the Gazette in November 2010 from the Reston family with great excitement for the future. “I want the Gazette to be a vibrant voice for the Vineyard community far into the future,” he said. In the interview with Ms. Martin, he reflected on the moment at hand. “I’ve never owned a newspaper and I probably won’t again,” he said. “We’ve got to keep this the kind of paper it has been: a country, sophisticated, wonderful paper on a unique Island with unique people.”

As for the wisdom of the investment, he said: “This is a different kind of investment. It’s an investment in preserving something that’s worth preserving. Newspapers are an important part of democracy.”

The following year he hired Jane Seagrave, a journalist and top executive at the Associated Press, as Gazette publisher.

He was remembered warmly this week by friends and acquaintances. “A wise, wise man,” said Sarah Bartlett, dean of the CUNY Graduate School of Journalism in New York who authored a book about K.K.R. and is a family friend. “He always asked the most insightful questions that always made you think harder about things you thought you knew the answers to.” She said his interest in journalism was piqued following the purchase of the Gazette. “Being able to help a local community paper play an essential role in community building — that was thrilling for him,” Ms. Bartlett said.

Davis Weinstock, a Chilmark resident who with his wife Betsy is a longtime family friend, remarked on Mr. Kohlberg’s extraordinary strength of character. “He was enormously interested in you no matter who you were,” Mr. Weinstock said. “He felt he already knew about himself; he not only didn’t need any hand holding as a friend but it was all about you. You had 100 per cent of his attention.”

In addition to his wife Nancy, he is survived by four children, Karen Kohlberg Davis of Petersham, Pamela Kohlberg of Chestnut Hill, James A. Kohlberg of Portola Valley, Calif., and Andrew S. Kohlberg of Del Mar, Calif.; 12 grandchildren and three great-grandchildren.

Funeral services will be private.