Harry D. Jacobs High School (commonly referred to as Jacobs or HDJ) is a public high school for students in grades 9 through 12 located in Algonquin, Illinois, a suburb of Chicago, serving students from the west half of the Village of Algonquin and its surrounding areas, including Lake in the Hills, Gilberts, some of Sleepy Hollow, some of Carpentersville, and some of West Dundee, Illinois.