Monticello (/ˌmɒntɪˈsɛloʊ/ MON-tih-SEL-oh[1]) is a village located in Thompson in Sullivan County, New York, United States. The population was 7,173 at the 2020 census.[2] It is the seat for the Town of Thompson and the county seat of Sullivan County.[3] The village was named after the residence of Thomas Jefferson.