St. Margaret Parish was established by the Catholic Diocese of San Diego in 1977 to better serve the rapidly developing Oceanside area. Until then, this section of the city was served by Mission San Luis Rey and the downtown parish of Mary, Star of the Sea.

Our parish is dedicated to St. Margaret of Scotland, and its founding pastor was Father George Sproul (R.I.P.). Father William Gold (Ret.) served as pastor from 1978-2001, who built the church hall. Father Cávana Wallace, who served as pastor from 2001-2021, oversaw the design and building of the parish church which was dedicated on November 4th, 2007. The present pastor is Father William Kernan. 

St. Margaret lived in the middle of the 11th century. She is venerated throughout the Church as a saintly mother, a fruitful wife, and a model queen. She is an example of Christian discipleship especially through her charity to the poor, particularly orphans. She was devoted to the Scriptures, was a liturgist, and had an active interest in sacred architecture and civil affairs, particularly during times of political unrest.