St. Thomas High School (French: École secondaire St. Thomas) is an English-language public high school in the municipality of Pointe-Claire, in Quebec, Canada. Founded in 1960, it was originally a Roman Catholic foundation, and it is a member of the International Baccalaureate Organization's certified Middle Years Programme. The school is the second-largest high school operated by the Lester B. Pearson School Board, after John Rennie High School, which is also located in Pointe-Claire. For the 2008 school year, St. Thomas High School ranked 1 out of all 466 schools in the province.