Loretto Abbey Catholic Secondary School (sporadically known as Loretto Abbey CSS, LACSS, Loretto Abbey, LAT, Loretto Abbey Toronto or Abbey) is an all-girls Catholic secondary school in Hogg's Hollow neighbourhood of Toronto, Ontario, Canada. Established by the Loretto Sisters in 1847, it is one of Toronto's oldest educational institutions and is part of the Toronto Catholic District School Board (then the Metropolitan Separate School Board) since 1986.