The official opening of St. Mary School in Carleton Place was celebrated on September 17, 1959. St. Mary School started out as a three-room school house with 85 students and within 40 years, grew into a large school of over 580 students and a staff of 45.

In 2003, it was once again a small school sharing half of its population with the new St. Gregory School.

In 2008, the two schools were reconfigured and junior kindergarten to grade 3 is now offered at St. Gregory School and grade 4 to 6 is offered at St. Mary School.

Our sister high school is Notre Dame in Carleton Place which offers grades 7-12.