Middletown Township is a township in Delaware County, Pennsylvania, United States. The population was 15,807 at the 2010 census. The Pennsylvania State University has an undergraduate satellite campus called Penn State Brandywine located in the north-central portion of the township. Located outside of Philadelphia, it constitutes part of the Delaware Valley.

The Delaware Valley, sometimes referred to as Greater Philadelphia or the Philadelphia metropolitan area, is a metropolitan region in the Northeast United States that centers around Philadelphia, the nation's sixth-most populous city, and spans parts of four U.S. states: southeastern Pennsylvania, southern New Jersey, northern Delaware, and the northern Eastern Shore of Maryland. With a core metropolitan statistical area population of 6.288 million residents and a combined statistical area population of 7.366 million as of the 2020 census, the Delaware Valley is the eighth-largest metropolitan region in the nation and North America, and the 68th-largest metropolitan region in the world.