The Ottawa Catholic School Board (OCSB, known as English-language Separate District School Board No.

53 prior to 1999[2]) is a publicly funded separate school board in Ottawa, Ontario, Canada.

[3] It employs approximately 4,777 people (full-time equivalents) and operates 84 schools in the greater Ottawa area, with a total student population of approximately 44,200.

Merging of the former Ottawa and former Carleton Roman Catholic School Boards resulted in the establishment of the Ottawa-Carleton Catholic School Board on January 1, 1998.

The board changed its name to the Ottawa Catholic School Board on March 27, 2007, to emphasize the commitment to Catholicity and to reflect the amalgamation of the City of Ottawa.