Ardsley is a village in Westchester County, New York, United States. It is part of the town of Greenburgh. The village's population was 4,452 at the 2010 census. The Ardsley post office serves the entire village of Ardsley plus some nearby unincorporated sections of Greenburgh. The Ardsley Union Free School District includes the entire village of Ardsley plus parts of the village of Dobbs Ferry and unincorporated parts of Greenburgh. Ardsley has a library that is a member of the Westchester Library System.