St. Louis Catholic Elementary School, Mimico

The Toronto Catholic District School Board (TCDSB, known as the English-language Separate District School Board No. 40 prior to 1999) is an English-language public-separate school board for Toronto, Ontario, Canada, headquartered in North York. It is one of the two English boards of education serving the city of Toronto.

The board was founded on April 2, 1953 as the Metropolitan Separate School Board (MSSB) when nearby separate school districts were amalgamated as a singular separate school board in Metro Toronto. In addition to English-language schools, the board also operated a handful of French-language schools by the Conseil des écoles catholiques du Grand Toronto (CECGT), the board's French unit. In 1998, the MSSB was renamed and reorganized into the Toronto Catholic District School Board leaving the board with anglophone schools while the francophone schools that were previously operated by CECGT were amalgamated with nearby French school boards in the region to form Conseil scolaire de district catholique Centre-Sud.

With more than 84,000 students, the TCDSB is one of the largest school boards in Canada, and is the largest publicly funded Catholic school board in the world.