Archbishop Riordan High School is a diocesan, all-boys Catholic high school established by the Society of Mary in San Francisco, California. It is part of the Roman Catholic Archdiocese of San Francisco. Originally called Riordan High School, the school was named after Archbishop Patrick William Riordan, the second Archbishop of San Francisco, and opened in the fall of 1949. In 1990, "Archbishop" was officially added to the school's name.