Monsey is a hamlet and census-designated place in the town of Ramapo, Rockland County, New York, United States, located north of Airmont, east of Viola, south of New Hempstead, and west of Spring Valley. The village of Kaser is surrounded by the hamlet of Monsey. The 2020 census listed the population at 26,954; a 46% increase since the 2010 census.

Ramapo is a town in Rockland County, New York, United States. It was originally formed as New Hampstead, in 1791, and became Ramapo in 1828. It shares its name with the Ramapo River. As of the 2020 census, Ramapo had a total population of 148,919, making it the most populous town in New York outside of Long Island. If all towns in New York were cities, Ramapo would be the 12th-largest city in the state of New York.