Marbletown is a town in Ulster County, New York, United States. The population was 5,607 at the 2010 census.
According to the United States Census Bureau, the town has a total area of 55.2 square miles (143 km), of which, 54.6 square miles (141 km) of it is land and 0.6 square miles (1.6 km) of it (1.11%) is water.
Rondout Creek and Esopus Creek flow through the town.
As of the census of 2000, there were 5,854 people, 2,386 households, and 1,598 families residing in the town. The population density was 107.3 people per square mile (41.4/km²). There were 2,846 housing units at an average density of 52.1 per square mile (20.1/km²). The racial makeup of the town was 95.46% White, 1.38% African American, 0.22% Native American, 0.70% Asian, 0.53% from other races, and 1.71% from two or more races. Hispanic or Latino of any race were 2.07% of the population.
There were 2,386 households out of which 30.6% had children under the age of 18 living with them, 55.4% were married couples living together, 7.8% had a female householder with no husband present, and 33.0% were non-families. 26.1% of all households were made up of individuals and 9.3% had someone living alone who was 65 years of age or older. The average household size was 2.43 and the average family size was 2.96.
In the town, the population was spread out with 23.2% under the age of 18, 4.9% from 18 to 24, 27.5% from 25 to 44, 31.2% from 45 to 64, and 13.2% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 97.2 males. For every 100 females age 18 and over, there were 93.4 males.
The median income for a household in the town was $46,250, and the median income for a family was $54,085. Males had a median income of $40,640 versus $30,130 for females. The per capita income for the town was $23,962. About 4.4% of families and 7.3% of the population were below the poverty line, including 7.5% of those under age 18 and 2.9% of those age 65 or over.