The name Agincourt is often used to refer to a larger area of northwest Scarborough rather than just the officially recognized neighbourhood.

The section of Agincourt west of Midland Avenue belongs to the electoral district of Scarborough—Agincourt, while the section to the east is part of Scarborough North (federal, previously Scarborough—Rouge River) or Scarborough—Rouge River (provincial, until the 2018 provincial election, when it will be replaced with Scarborough North).

The name of the settlement was after the site of Henry V's decisive English victory over French forces in 1415.

The original crossroads of Agincourt is located at Midland Avenue and Sheppard and served a rural agricultural population.

A secondary school that later evolved into Agincourt Collegiate Institute, was established in 1915 on the second floor of the same building.

A second station was built east of the crossroads, northside of Sheppard Avenue and west of Brimley Road, on what is today CP Rail track that runs from downtown Toronto diagonally northeast through the neighbourhood.

In addition to secondary schools, TDSB also operates institutions which provide primary education.