Syosset /saɪˈɒsɪt/ is a hamlet and census-designated place (CDP) in Nassau County, New York, United States, in the northeastern section of the Town of Oyster Bay, on the North Shore of Long Island. Syosset is an affluent community, well known for its school district, and is served by the Syosset railroad station, the Syosset Post Office, the Syosset Central School District, the Syosset Public Library, the Syosset Fire Department, and the Jericho Water District. The population was 18,829 at the 2010 census. Syosset is located approximately 32 miles (50 km) east of Midtown Manhattan, 14 miles (20 km) east of eastern border with Queens, 23 miles (40 km) southeast of the Throgs Neck Bridge, and 168 miles (270 km) southeast of Albany, the state capital. It is also in close proximity to beaches, with Jones Beach only 19 miles (30 km) south of the town. It borders Oyster Bay and Laurel Hollow to the north, Woodbury to the east, Plainview and Hicksville to the south, and Jericho to the west, Service is accessible to New York City by the LIRR and the Long Island Expressway by car.

In Syosset, the median home value is $749,628.^[2]

Syosset is located at 40°48′46″N 73°30′03″W ^[10] .^[3]

According to the United States Census Bureau, the CDP has a total area of 5.0 square miles (13 km2), all land.

As of the 2010 U.S. Census,^[1] there were 18,829 people, 8,131 households, and 5,307 families residing in the CDP. The population density was 3,719.7 per square mile (1,434.8/km2). There were 6,354 housing units at an average density of 1,274.5/sq mi (491.6/km2). The racial makeup of the CDP was 66.2% White, 0.9% African American, 0.2% Native American, 26.5% Asian, 0.01% Pacific Islander, 0.8% from other races, and 1.6% from two or more races. 4.9% are Hispanic or Latino of any race. Syosset, like many other towns on the North Shore of Long Island, has a large Jewish population, as well as a large number of residents of East Asian origin. 31.9% of the population spoke a language other than English at home, mostly Chinese or Korean.

There were 8,131 households out of which 25.6% had children under the age of 18 living with them, 75.5% were married couples living together, 7.5% had a female householder with no husband present, and 14.4% were non-families. 12.6% of all households were made up of individuals and 7.6% had someone living alone who was 65 years of age or older. The average household size was 3.05 and the average family size was 3.33.

In the CDP, the population was spread out with 26.0% under the age of 18, 5.6% from 18 to 24, 26.3% from 25 to 44, 27.1% from 45 to 64, and 15.0% who were 65 years of age or older. The median age was 41 years. For every 100 females, there were 96.2 males. For every 100 females age 18 and over, there were 90.5 males.

The median income for a household in the CDP was $158,145, and the median income for a family was $181,648. Males had a median income of $109,742 versus $77,038 for females. The per capita income for the CDP was $59,140. About 1.6% of families and 2.8% of the population were below the poverty line, including 2.4% of those under age 18 and 4.3% of those age 65 or over.

Syosset is protected by the firefighters and EMT's of the Syosset Fire Department (SFD), which consists of five all-volunteer fire companies and one all-volunteer EMS company. The Syosset Fire Department currently operates out of 3 Fire Stations, located throughout the area, which encompasses Syosset, Woodbury, and parts of Muttontown, Oyster Bay Cove, Laurel Hollow, Cold Spring Harbor, East Norwich, Jericho, Hicksville, and Plainview. At 14.4 square miles, it is the largest coverage area in Nassau County. They operate a fire apparatus fleet of 5 Engines, 2 Trucks, 1 Rescue, 3 Ambulances, and several special, support, and reserve units.

The 11791 ZIP code includes portions of the incorporated villages of Muttontown, Laurel Hollow and Oyster Bay Cove which results in a Syosset mailing address. Consequently, the news and media often erroneously report Syosset as the hometown of notable residents of said villages.