Monticello is a village located in Thompson, Sullivan County, within the Catskills region of New York, United States. It is the seat for the town of Thompson, and the county seat of Sullivan County. The population was 7,173 at the 2020 census. The village was named after the residence of Thomas Jefferson.

Thompson is a town in the southern part of Sullivan County, New York, United States. The population was 16,550 at the 2020 census. The town is named after William Thompson, an early settler.