private, coeducational college-preparatory school (grades 9–12) in Andover, Massachusetts, U.S. Features of its 500-acre (200-hectare) campus include a bird sanctuary, the Addison Gallery of American Art, and the Robert S. Peabody Museum of Archaeology.

It was founded as a boarding school for boys in 1778 by Samuel Phillips, who later became president of the state senate of Massachusetts. Andover is the oldest incorporated academy in the United States. Sons of some of the nation's most influential families have enrolled there, including Washingtons and Lees from Virginia and Lowells from Massachusetts. In 1973 Andover merged with adjoining Abbot Academy for girls, established in 1829 as the first incorporated New England school for girls. Total enrollment is about 1,200.