For this club, life begins at 50 (%)

When David Ludlow's wife died in a climbing accident 11 years ago, her death transformed him into a multimillionaire: He inherited Vanda Sendzimir's share of her family fortune, a $5 million trust that generates an annual interest of about $300,000. Then a freelance photographer with a passion for social justice issues, the Jamaica Plain man was plunged into a swirl of shock, guilt, and confusion.

"I've always been very left-wing politically and all of a sudden I was living incredible inequality," said Ludlow, 64. "Suddenly I was in the upper 1 percent of the population in terms of wealth, and I felt terrible about that for a long time."

So he did something radical, and something that many people might consider insane: He decided to give away half his annual income.

In doing so, Ludlow joined a small, unusual, and growing community: The 50% League, an Arlington-based group of people who contribute at least half their income, business profits, or net worth to charity. Members from across the country have been welcomed into an elite circle of givers and asked to share their stories publicly, even if anonymously, to inspire other givers.

Their motivations are manifold: Some give out of a sense of fairness, personal satisfaction or a desire for simplicity; others are driven by religious faith or dedication to a cause.

Many are anonymous philanthropists, and not all of them have great wealth: Some are members of the middle class, but have chosen to survive on less so they can give more. Above all, they aim to stand as role models, and to encourage others of all income levels to think about their giving potential.

"We want people to be able to find someone they can relate to and say, 'This person is giving substantially more than I've ever dreamed of giving, so maybe I should work at what I can give,' " said Christopher Ellinger of Arlington. With his wife, Anne, Ellinger founded a nonprofit initiative called Bolder Giving that launched The 50% League in May. It now has nearly 90 members, and has drawn interest from many more.

"If at first 50 percent seems ridiculous, then what amount could be a stretch for them? For some people that might be 5 or 10 percent," added Ellinger, 50, who received an unexpected inheritance of several hundred thousand dollars when he was in his early 20s and chose to give slightly more than half of it to charitable groups. "Most people aren't challenged to even think about what they want to give."

In most cases, an unexpected windfall or a personal fortune that promises lifelong wealth are reasons for celebration and, often, spending: a second home, a luxury car, a lavish vacation, a boat or private plane.

But other people feel conflicted about their wealth. Are they deserving of this material bounty? If they donate it to charity, how can they be sure the money will be used wisely? If they work, are they depriving another person of a job? Should they tell their friends about their wealth? If they donate a large portion of their wealth, do they risk financial insecurity in the future?

"Many people would say, 'Oh, I wish I had those problems,' and I can understand that," said Jennifer Ladd, who was 21 when she received her share of her family's Standard Oil fortune, an amount that, at its height through appreciation, reached $1.2 million. "But here I am living in a society where many people do not have what I have. How do I live with that? How do I make sense of that?"

Ladd, who is now 54 and lives in Northampton, is also a member of The 50% League. Self-conscious about her wealth and committed to trying to close the gap between rich and poor, she began funding charitable causes. In 2004, she decided to give half of her remaining inheritance to groups, including a nonprofit she cofounded called Class Action, that support economic justice and social change.

"As a society we'd be a lot healthier if money flowed as opposed to being pocketed," Ladd said. "I'm not saying everyone should do what I do. But if you have more than you need, consider giving it out, because it's really exciting and it can be quite fun and very rewarding."

Mike Lapham was 16 when his parents gave him startling news: The Upstate New York paper mill where his grandfather worked was actually owned by his family, and he would soon receive enough dividend-producing stock so that he might not need a job. But Lapham, a Jamaica Plain resident who belongs to The 50% League, chose to work anyway and to give away between 50 percent and 75 percent of his annual income, comprising a modest salary and the $80,000 in dividends he typically received annually.

He has reduced his giving now that he is married and has two children, but he has given away more than a half-million dollars "For me, inheriting money that I didn't work to earn or didn't take any risks to earn definitely makes me question whether it's even mine at some level," said Lapham, 45, the director of Responsible Wealth, a project of the Boston nonprofit organization United for a Fair Economy, which works to reduce economic inequality. "So for that reason it's been easy for me to think about giving it away."

To belong to The 50% League, members must have donated 50 percent or more of their income or business profits for at least three years, or 50 percent or more of their net worth at some point in their lifetime. The group includes Grace Ross, the former Massachusetts gubernatorial candidate, who qualified by giving away a $250,000 inheritance and $400,000 in proceeds from a house she also inherited and then sold. She donated the money to social justice groups and anti- poverty projects.

Some of the league members, none of whom are billionaires, speak publicly about what motivates their philanthropy, seeking to inspire other givers with their personal stories.

At Bolder Giving, the Ellingers and other staff members also speak frequently to gatherings of wealthy people and their advisers to urge them to explore their giving potential. They connect philanthropic-minded people with financial planners so they can determine how much they could be giving away. They link givers with grant-making organizations that can help them choose which charities to fund.

And they prod philanthropists and charities to question basic assumptions about philanthropy, such as the conventional wisdom that principle should never be spent, a philosophy rejected by Frank Butler, a retired chief executive of a subsidiary of Kodak.

"I always dip into principle," said Butler, 77, of Topsfield, whose combined annual pension and Social Security income is about $80,000, of which he gives away between 50 percent and 75 percent annually, largely to religious groups.

Butler also has substantial retirement savings into which he dips. One year, he and his wife, Ruth, gave away more money than they brought in, he said. Their goal is to have spent all their wealth by the time they die, leaving no inheritances for their two daughters.

"Of all the enjoyable things in our lives outside of our family," said Butler, whose philanthropy is motivated by his Christian faith, "our giving experiences have been the most fun."

Ludlow, too, has found tremendous joy in giving. "I feel incredibly privileged, and I still feel guilty about that," said Ludlow, who has used much of the money he inherited from his late wife, whose fortune came from a steel-processing method invented by her father, to fund grass-roots groups led by low-income people of color. He also funds Social Justice Education, a nonprofit organization he founded to train community leaders.

"But it's given me tremendous meaning in my life to give as much as I can away."

Sacha Pfeiffer can be reached at pfeiffer@globe.com.