Saint Patrick's Grammar School is a Catholic grammar school located in Downpatrick, County Down, Northern Ireland. It is currently owned by the De La Salle Brothers. It has an enrolment of around 725 students, with girls admitted at 6th form level. Pupils come from all over the East Down area. Working to support the ideals of this Lasallian School is a staff of 75 lay teachers. Recently, the school has been awarded the Investor in People award, and has been named a specialist school in humanities by the Department of Education.

Downpatrick is a town in County Down, Northern Ireland. It is on the Lecale peninsula, about 21 mi (34 km) south of Belfast. In the Middle Ages, it was the capital of the Dál Fiatach, the main ruling dynasty of Ulaid. Its cathedral is said to be the burial place of Saint Patrick. Today, it is the county town of Down and the joint headquarters of Newry, Mourne and Down District Council. Downpatrick had a population of 11,545 according to the 2021 Census.