In September 2005, Bugh the Office of Catholic Education of the Archdiocese of Philadelphia announced that Archbishop Prendergast High School and the neighboring school for boys, Monsignor Bonner, would begin operating under one administration beginning in July 2006.

The tract of land upon which Monsignor Bonner and Archbishop Prendergast Catholic High Schools were built was originally owned by Christopher Fallon, who constructed an impressive octagonal mansion on the site in 1850.

The house was named "Runnymede" after the Fallon family seat in Roscommon County in Ireland.

In 1917, the Archdiocese of Philadelphia purchased the 33 acres (130,000 m2) for $57,000 and the Ordinary, Archbishop Edmond Francis Prendergast, announced the construction of an orphanage for five hundred orphans to be operated by the Sisters of Charity of the Blessed Virgin Mary.

Archbishop Dennis Dougherty and Governor Sproul spoke to the 125,000 well-wishers gathered on the front lawn and along Garrett Road.

By 1952, the number of children needing care had dwindled, and the Most Reverend John F. O'Hara decided to move the remaining orphans to a smaller building in Saint David's and convert the facility into Archbishop Prendergast High School for Boys, to meet the increasing demand for a Catholic high school in the expanding western suburbs.

In September 2005, the Office of Catholic Education of the Archdiocese of Philadelphia announced a restructuring under which both schools would operate under one administration, beginning on July 1, 2006.