Sacred Heart-Griffin High School, often abbreviated SHG, is Springfield, Illinois' largest private high school. The school is Roman Catholic and is located in the Roman Catholic Diocese of Springfield in Illinois. It opened in the fall of 1988 after Sacred Heart Academy, an all-girls Catholic high school merged with Griffin High School, an all-boys Catholic High School located across the street. Even prior to the merger, certain classes at both schools were taught on a co-educational basis.