Two brothers who were Episcopal clergymen—The Rev. Theophilis M. Reilly, and the Rev. William M. Reilly—conducted St John's Academy in Burlington, according to Cliff Brunker of the Historical Society of Haddonfield. In 1871 they moved the school to Haddonfield when they purchased 110 acres that were part of the high ground at 310 Centre St.
In 1878, a sister school for girls, St Agnes Academy, was founded. It was housed opposite to the boys' school on the corner of Lakeview Avenue and Centre Street.
Both schools were under the direction of Mrs. William M. Reilly.