A Catholic high school in the South End has secured funding for its tuition assistance program and more, for the next century.

Cathedral High School announced the successful completion of a three-year $60 million fundraising drive that was triggered by an anonymous alumnus’ offer to match up to $30 million in donations.

“Our anonymous donor knew what this school meant to him,” said Cathedral President Dan Carmody. “He knew how he started here. He knew some of the challenges he faced and what this school helped him to overcome. His very simple goal was to make sure that never ends.”

Cathedral serves 340 students from 40 different communities, with many coming from Dorchester, Mattapan, Roxbury and Hyde Park. About 98% of students are either Black or Latino. They speak more than 10 languages, and their families come from more than 20 countries.

A large portion of the $60 million endowment will be used to fund the school’s tuition assistance program. Carmody said the cost to educate each student is about $21,000 with a stated tuition cost of $15,700. But every single accepted student automatically receives an automatic opportunity grant that brings the tuition down by half. On top of that, more than 95% of students receive additional needs-based assistance. Financial aid brings the average tuition cost to around $2,200, but many families pay significantly less.

“Our goal is to provide a high-quality rigorous education at a fraction of what it would normally cost,” Carmody said. “We also recognize that if you’re a family who is working hard to make ends meet, that $2,200 can still seem like a big nut. So, we’re really grateful that for families who need further assistance, we’re able to do that.”

The anonymous donor, a 1954 alumnus who has been known by Cathedral students and families through their many years of involvement with the school, asked Carmody what it would take for the school to continue its mission in perpetuity. Their offer to meet half of that requirement sparked a contagious enthusiasm for generosity. Seven other donors contributed at or above the $1 million mark, and countless smaller donations made their goal achievable.

Fundraising efforts will continue as tuition costs only make up 9% of Cathedral’s annual revenue.

“Most independent private schools, they’re counting on 75% to 80% or more of their revenue to come from tuition. Where ours is only 9%, we have to raise all of the rest,”

Carmody said. “We’re not passing on that financial gap to students and families. We’re saying we still need to raise it.

Much of Cathedral’s fundraising successes are had through events aimed at demonstrating the impact Cathedral has on its students to the community. A mission that is now further boosted by its proven longevity.

“A lot of people were excited to get behind this because they knew they were contributing to something that had legs and was going to last for a long, long time and unfortunately that hasn’t always been the case with Catholic schools recently in Boston,” Carmody said.

Just last year, three Catholic schools closed in Massachusetts. Cambridge Matignon School, Saint Joseph Prep Boston in Brighton and Bishop Connolly High School in Fall River all closed their doors, while Mount Alvernia High School in Newton announced it would be merging with Fontbonne Academy in Milton.

“Cathedral for a long time has kind of fit into that category of small Catholic school and ‘Are we going to make it?’” Carmody said. “I think now we all know and can say with confidence that, ‘Yeah we’re here to stay and we’re here for a long time and we no longer face that fear.’”