West Islip is a hamlet and CDP located in the Town of Islip in Suffolk County, New York, United States. Situated on the South Shore of Long Island, the population of the CDP was 28,335 at the time of the 2010 census.
West Islip is located at 40°42′54″N 73°17′52″W (40.715008, -73.297746).
According to the United States Census Bureau, the CDP has a total area of 6.8 square miles (17.5 km2), of which 6.3 square miles (16.4 km2) is land and 0.42 square miles (1.1 km2), or 6.46%, is water.
Great South Bay, Jones Beach Island and Fire Island lie to the south. Babylon and North Babylon form the western border. Bay Shore lies to the east, and in the north West Islip borders on Deer Park and Brentwood. West Islip is 45 miles (72 km) east of Manhattan and 45 miles (72 km) west of Southampton, New York. West Islip's western boundary is a natural one formed by Sampawams Creek, Hawley's Lake, Deer Lake and Swan Creek.
The first people to settle in the area were the Secatogue Indians. The unearthing of an Indian burial ground north of West Islip beach enabled historians to reconstruct a village of these Indians who lived along the edges of the Great South Bay, Sampawams Creek, Trues Creek and Willetts Creek.
In the early 17th century, the West Islip area came under the influence of the Dutch. In 1664 it came under English rule when the Duke of York claimed Long Island with the permission of King Charles II.
During the 19th century, the community became a popular haven of wealthy estate owners.