St. William School was founded in 1947 as the primary ministry of St. William Parish. The original building had a school with eight classrooms and a temporary Church. It was staffed by Ursuline Sisters and had a wonderful reputation in the Euclid Community. In 1951, a second floor was built consisting of four classrooms and a large social hall. In 1955, six classrooms and a basement were added.
As part of a restructuring process in the Diocese of Cleveland, Ss. Robert & William Catholic Parish was formed from the former St. Robert Bellarmine Parish and St. William Parish at the former St. William campus. Recognizing the shifting demographics, financial constraints, and shortage of priests, the Diocese engaged in a clustering process in 2006. From that process the city of Euclid merged six parishes into three new parish communities in late 2009 and early 2010. The new parishes are St. John of the Cross (merger of St. Felicitas & St. Paul), Our Lady of the Lake (merger of Holy Cross and St. Christine) and Ss. Robert & William (merger of St. Robert & St. William).
Ss. Robert & William was founded on January 3, 2010. Fr. John D. Betters was appointed founding pastor, by Cleveland Bishop, Richard G. Lennon. On January 31, 2010, Bishop Roger Gries (Auxiliary Bishop of Cleveland) installed Fr. John as the first Pastor of Ss. Robert & William Catholic Parish.
In 2014, a partnership was formed between St. John of the Cross and Ss. Robert and William to educate the students of both parishes.