Oeiras International School sits in a green setting in Barcarena, in the Oeiras area. It is an IB school from start to finish, with the Primary Years, Middle Years and Diploma Programmes.
From September 2026 the school runs more than one campus in Barcarena, with the youngest year groups on a separate primary site. Children join from Year 1, at age 5, and can stay until Year 13.
OIS can be a practical choice if you’re living between Cascais and Lisbon. It’s a good idea to ask which campus your child would start on, and how the bus routes work from your area.