Corpus Christi Elementary School in Mineola, operating since 1922, will shut down after classes end in June, the diocese said.
"It is never easy to close a school," said Sister Joanne Callahan, diocesan superintendent of schools. "But the demographics and enrollment decline left the parish no alternative."
Diocesan officials said enrollment at Corpus Christi dropped by 58 percent in the last decade, from 431 students to 183. This year's first and second grades had just 14 and 12 students, respectively.
The Diocesan Education Commission and Tomorrow's Hope Foundation - a nonprofit that offers scholarships to Catholic school students - worked with the Corpus Christi parish and school for the last four years trying to avoid the closing, the diocese said. But in the end, it wasn't enough.
"I am saddened by the closing of Corpus Christi School," said its principal, Susan M. Anaischik. "It has had a very rich history of academic excellence, cultural diversity, and formation in our Catholic faith."
Rockville Centre had bucked a nationwide trend by avoiding the closure of elementary schools since 2005. Some 31 new Catholic elementary or high schools opened in the United States last year, but 162 closed or consolidated, according to the National Catholic Education Association.
Enrollment in Catholic schools nationwide has dropped from a historic high of 5.2 million in 1965 to 2.2 million today.