 The Scarborough School was founded in 1913 by Frank and Narcissa Vanderlip for their six children and the children of friends and neighbors . Having met educator Maria Montessori during their European travels , the Vanderlips pioneered the Montessori method at the Edward Harden Mansion in nearby Sleepy Hollow by creating the first Montessori school in the United States , in 1912 . Frank Vanderlip 's sister Ruth was married to Harden ; the families maintained close ties . After a year existing in two rooms of the Harden residence , the school moved to the River Gate House at the north end of River Road and the Beechwood estate . 
