In 1850, St. Paul Parish was established with Rev. John Scollard as its first pastor. Determined that the children of the parish be educated in a Catholic atmosphere, he opened the first Catholic school in Princeton. This school was in the basement of the church at 182 Nassau Street. Later that property was sold and the church and school were moved to 214 Nassau Street.

In 1878, Fr. Moran obtained the help of the Sisters of Mercy to administer the school and Religious Education programs as well as minister to the sick and indigent of the parish. Sister Gabriel Redigan was superior of the first six teaching sisters of St. Paul School.

Fr. Moran built a separate school building in 1880 at 218 Nassau Street. The construction of the current school (on the foundation of Fr. Moran's school) began in 1930 and was initiated by Rev. Dr. Patrick Clune, pastor and previous Superintendent of Schools of the Trenton Diocese.

The school has grown to its present enrollment of approximately 400 students in grades PK3 - 8. The entire school is networked with internet access in each classroom as well as the labs.

The most recent addition to SPS was the establishment of the Little Lions Preschool with brand new purpose-build 3-year-old and 4-year old classrooms in the renovated Sisters of Mercy Early Learning Center.