Central Islip is a hamlet and census-designated place (CDP) within the Town of Islip in Suffolk County, New York, United States. The population was 34,450 at the 2010 census.
Prior to the arrival of European settlers, the Secatogue tribe of Algonquin native-American people lived in the area now known as Central Islip.
In 1842, the Long Island Rail Road's eastward expansion reached the area, and the Suffolk County Station was opened up. The Suffolk County Station, became the commercial center for housing. With that being done the name Central Islip was thus born, and applied to a new station built in 1873 further to the east. The modern Central Islip station is in a different location from all of its predecessors.
In 1889, what became the Central Islip Psychiatric Center opened. By 1955, it housed over 10,000 patients. It closed in 1996.
In the mid-1990s, Central Islip began a resurgence, with new housing developments, commercial properties, and government complexes.