St. Theresa of Lisieux Catholic High School is a Catholic high school in Richmond Hill, a suburb of the Greater Toronto Area in Canada.

St. Theresa's athletics offers a wide variety of sports and other recreational events held throughout the school year.

St. Theresa of Lisieux Catholic High School also offers the AP (Advanced Placement) and pre-AP program for students.

Students in this regular program have the opportunity to participate in differentiated courses in English, Mathematics, Science, and Social Sciences.

St. Theresa of Lisieux currently ranks 1st in Ontario out of 746 high schools according to the Fraser Institute, tied with four other schools.