Nesconset is a hamlet and census-designated place (CDP) in the town of Smithtown, located in Suffolk County, Long Island, New York, United States. The population was 13,387 at the 2010 census.
Nesconset is located at 40°50′46″N 73°9′2″W (40.846090, -73.150573).
According to the United States Census Bureau, the CDP has a total area of 3.8 square miles (9.8 km2), all land.
As of the census of 2000, there were 11,992 people, 3,964 households, and 3,226 families residing in the CDP. The population density was 3,133.5 per square mile (1,208.9/km2). There were 4,227 housing units at an average density of 1,104.5/sq mi (426.1/km2). The racial makeup of the CDP was 94.37% White, 0.96% African American, 0.11% Native American, 3.11% Asian, 0.07% Pacific Islander, 0.57% from other races, and 0.82% from two or more races. Hispanic or Latino of any race were 3.36% of the population.
There were 3,964 households, out of which 39.7% had children under the age of 18 living with them, 71.5% were married couples living together, 7.1% had a female householder with no husband present, and 18.6% were non-families. 14.7% of all households were made up of individuals, and 4.0% had someone living alone who was 65 years of age or older. The average household size was 4.97 and the average family size was 4.31.
In the CDP, the population was spread out, with 25.7% under the age of 18, 6.5% from 18 to 24, 32.3% from 25 to 44, 25.8% from 45 to 64, and 9.6% who were 65 years of age or older.