NEW YORK — When Catholic schools in Boston, New York and Minneapolis open again in September, they’ll have financial contributions at their disposal, many from a surprising source — non-Catholics. Who are the philanthropists, and why do they give?

Take retired hedge-fund adviser Robert Wilson, who made his millions as a growth-stock investor at his firm, Wilson Associates, and describes himself as an atheist. He took $15,000 in 1949 and turned it into $225 million by the time he retired in 1986 at the age of 60.

Then Wilson began giving it away.

Wilson says that he wants to donate 70% of his wealth before he dies. So far, he has given more than $550 million to charitable causes, including more than $28 million to the Archdiocese of New York to help Catholic schools.

Wilson began giving to archdiocesan schools in 1997 with a gift of $10,000. In 2007, Wilson gave a $22.5 million gift to support scholarships.

Like many who give to Catholic schools, Wilson does so because of Catholic schools’ educational achievement record.

“Most of what the Catholic schools teach are the three Rs,” Wilson told Bloomberg News. “And they do it better than the union-controlled inner-city schools.”

Faced with Catholic schools having to close across the country, Wilson’s most recent gift — $5.6 million this summer — will fund the Catholic Alumni Partnership, a program he founded that helps elementary schools locate alumni and recruit them as potential donors.

According to the archdiocese, 95% of New York Catholic school alumni have not been supporting the schools they attended.

“Every private school … relies on alumni support,” said Wilson.

Already, there has been fruit from the alumni effort. The program has raised more than $1 million from about 11,000 graduates.

“With a Catholic education, I can take the poorest kid in the most negative family situation and send him to college,” said Cardinal Edward Egan, New York’s former archbishop. “What Robert Wilson is giving us is hope for what can happen.”

Matching Grant

Andrew Redleaf, who grew up Jewish, also made his fortune as a financial investor. Redleaf is the founder and CEO of Minneapolis-based Whitebox Advisors, an investment firm that manages approximately $3 billion in assets.

When two members of Chesterton Academy’s board, who knew Redleaf, began telling him about the independent college preparatory school in St. Louis Park, Minn., Redleaf took an interest.

“After just two years we’ve been able to prove we were turning out a good product,” said Dale Ahlquist, president of the American Chesterton Society and founder of Chesterton Academy, which began in 2008 with just 10 students and now counts 38. “He was impressed that we had accomplished so much with so few resources.”

Redleaf gave three reasons for his decision to support the high school. He was concerned with the “national decline in educational achievement among young men.” He was impressed with the school’s ability to offer a “rigorous classical education at a price middle-class families can afford.” And he liked the school’s focus on Western civilization.

“What the folks at Chesterton call ‘the Catholic tradition’ are really foundational values of our civilization,” said Redleaf. “I hope many more non-Catholics … will join me in supporting that effort.”

Redleaf issued a challenge grant to the school, promising $75,000 if the school could raise a similar amount between May 17 and June 15.

Students, parents, faculty and others quickly jumped on board, soliciting donations from friends and family members — online and elsewhere. Students at the high school performed a talent show, raising approximately $3,000 toward the cause. In the end, Chesterton Academy surpassed its goal, raising a total of $94,861 from nearly 300 gifts from donors in 37 states and two foreign countries.

“Redleaf gave us half of what we needed for our operating budget,” said Ahlquist. “We’re set for this school year.”

Students of Other Faiths

Boston real-estate company executive Richard Henken also grew up Jewish, but he gives between $25,000 and $30,000 annually to Catholic schools. He’s primarily interested in giving because the schools help educate the poor.

Henken’s donations go to help the needy, especially those who reside in a 500-unit Cambridge, Mass., housing complex that his company helped improve. Henken’s donation is given on the condition that residents of the housing complex get first priority for the scholarships.

Others who are non-Catholic give because they themselves have children who have benefited from the education that the institutions offer. The Archdiocese of Boston estimates that about 20% of its 45,000 school children are not Catholic.

According to The Boston Globe, Henken is one of several prominent Jewish contributors in the Boston area who routinely donate to Catholic schools. The Globe also identified New England Patriots owner Robert Kraft; real-estate executive Robert Beal; Howard Kessler, who pioneered the concept of affinity credit-card marketing, and his wife, Michele; and businessman Jim Coppersmith as major donors.

Coppersmith told the Globe that he was impressed with the education that his son received at St. John’s Preparatory School. Coppersmith started Boston’s Inner-City Scholarship Fund’s annual fundraising dinner, which has continued since the late 1980s.

“[The Catholic school is] attractive because it touches a couple of different things Jews tend to care about — No. 1, it touches the poorest of the poor,” Barry Shrage, president of Combined Jewish Philanthropies told the Globe. “… And it does it through education.”

Tim Drake is based in