The Dalton School is a prestigious college prep school in the Ivy Preparatory School League. Founded in 1918 by Helen Parkhurst (a contemporary and colleague of Maria Montessori), Dalton was established as an "educational model that captured the progressive spirit of the age." (from wiki)
Notable folks that have attended the Dalton School include science-fiction writer Samuel R. Delany, actors Chevy Chase, Christian Slater and Claire Danes.
