Princess Margaret Secondary School (also known as PMSS or "Maggie") is a public secondary school in Penticton, British Columbia, Canada.

It is operated by School District 67 Okanagan Skaha.

The school includes a significant number of students from the local First Nations Penticton Indian Band and is located within the traditional Okanagan Nation territory.

[1] PMSS is named for Princess Margaret, Countess of Snowden, sister of Elizabeth II, Queen of Canada.

Due to a growing population at the south end of the city, an elementary school, Snowdon Elementary, was built on the grounds in the early 1960s, and students from Grades 7 - 10 attended PMS.