Thayer Academy (TA) is a private, co-educational, college-preparatory day school located in Braintree, Massachusetts, United States. The academy, conceived in 1871 at the bequest of General Sylvanus Thayer, the father of the United States Military Academy, and founder of the Thayer School of Engineering at Dartmouth College, was established in 1877. Thayer annually enrolls approximately 470 students in the Upper School (grades 9–12) and an additional 220 students in the Middle School (grades 6–8). The 34-acre (14 ha) campus is situated in the heart of Braintree and consists of eight buildings and 54 classrooms.