St. Theresa of Lisieux Catholic High School is a Catholic high school in Richmond Hill, a suburb of the Greater Toronto Area in Canada. The school is named after St. Theresa of Lisieux ("The Little Flower") for the little things that she did which changed people's lives. The school was founded by the York Catholic District School Board in 2002. The first graduating class was that of 2005. The graduating class of 2006 was the first class to have gone through all four grades at this school.