St. Margaret Mary School is a ministry of St. Margaret Mary Parish. The school opened in 1954 under the direction of Fr. Richard Maher and staffed by the Sisters of St. Francis of Clinton, Iowa. It opened with 145 students in grades one through six. In 1956, grades seven and eight were added. Kindergarten opened in 1984 and preschool started in 1997. The Extended Care program opened in 1987.

St. Margaret Mary School serves as the Catholic School for students from St. Margaret Mary, Our Lady of Guadalupe in Chino, St. Elizabeth Ann Seton in Ontario, and St. Paul the Apostle in Chino Hills. Most of our students live in Chino and Chino Hills with a few coming from Diamond Bar, Pomona, Ontario and Montclair. The community is one of diverse ethnic backgrounds and our student population reflects this diversity.

Recently, St. Margaret Mary School qualified to apply for the Blue Ribbon School Program. In order to qualify, schools need to be in the top 10% of schools in the state as indicated by standardized test scores.