Hackley was founded in 1899 as a college preparatory school for boys through the generosity of Mrs. Frances Hackley, who, in partnership with leading Unitarians of the era, sought to create a non-sectarian school that embraced Unitarian values of intellectual questioning and inclusiveness. A philanthropist with a deep commitment to education, Mrs. Hackley was among the founders of Barnard College, and helped in the development of the Manassas Industrial School for Colored Youth, as well as a number of vocational programs and kindergartens.
From its founding, Hackley would welcome students of diverse religious, economic, ethnic, and national origin within an ethos shaped by the school's Latin motto, Iuncti Iuvamus, which we translate as, "United, We Help One Another."
The school quickly outgrew its original home in Mrs. Hackley’s Tarrytown mansion, and Mrs. Hackley funded the purchase and construction nearby of the campus we know today. The first new buildings were in use by 1902, with the phrase that has represented the Hackley spirit for over a century -- “Enter Here To Be And Find A Friend”--engraved above the door.
Hackley has evolved since its founding into a co-educational K-12 day school with five-day Upper School boarding, increasing the number and variety of perspectives in its community while faithfully and vibrantly carrying our founder’s vision forward.