The historic school building was built in 1889, and is a three-story, eight-bay, brick building on a limestone base in the Late Victorian-style. It features a decorative brick corbel, small pedimented dormer, and three great flaring capped chimneys.[2] It was named for American lawyer, author, and amateur poet Francis Scott Key (1779–1843).
In 1988 over 75% of Key's students were under the poverty line.[5]
Prior to 1989 Key was a K-8 school. In 1989 the district decided to move grades 6-8 to Southwark School in order to relieve overcrowding at area elementary schools, and in turn the high school program Southwark Motivation, on the third floor of Southwark, was to be moved to South Philadelphia High.[6]
On June 10, 2015 an emergency notification was sent regarding asbestos found at Key.[7] District spokesperson Fernando Gallard stated that the district had discovered the asbestos before the notification, sent by Philadelphia city controller Alan Butkovitz to officials, was sent out, and that the problem had been fixed.[8]