Sacred Heart-Griffin High School, often abbreviated SHG, is a Catholic high school located in Springfield, Illinois, the city's largest private school. It is located in the Diocese of Springfield in Illinois. The school 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.