An anonymous donor in December gave $100,000, which will be used in part for tuition assistance, according to the parochial school.
OLSH announced this week that its annual fund balance is the largest in school history at $150,421.93, thanks to the sizeable donation.
"It was a very nice year-end gift," said Cheryl Karashin, OLSH vice president for advancement.
School officials said the donation will enable the school to keep tuition levels stable for the upcoming school year. Tuition for one student enrolled in the school is $7,600 with a $200 activity fee for the 2011-2012 academic year.
Karashin said the contribution marks one of the largest donations in the school's 80-year history.
"What it means for the school in general is that it will allow us to enhance the programs that we offer," Karashin said. "Being a Catholic, private school, it can help make the OLSH experience more affordable. That's why a portion of it is earmarked for tuition."
Karashin said the sluggish economy hasn't slowed outside financial contributions to the Woodcrest Avenue high school.
OLSH's annual fund balance has grown from less than $20,000 in 2005 to more than $150,000 with this latest donation. Karashin described the fund as the "cornerstone of the school."
"The OLSH community has really stepped in and continued to support us," she said. "While it's a difficult time for everyone in the country, I think people realize that it's a difficult time for schools as well."
Portions of the donation will be used to enhance the school's athletic and extracurricular offerings.
"I'd say that this donation and the others we've received clearly demonstrate that for many donors a philanthropic investment is a wise decision," she said.