Prison conditions similar to the supermax design were implemented as early as the 1800’s but soon abandoned because they were thought to impair the mental health of prisoners. This article discusses the use of prison segregation units in Auburn Prison in New York State, a well-known example of supermax-like conditions for prison inmates begun in 1821 and consistently evaluated by wardens such as Dr. Thomas Cleveland. Dr. Cleveland documented the psychological impact of the prison segregation experiment arguing that demonstrable changes in mental health occurred with changes in the conditions of prisoners’ confinement. Describing an identical prison experiment conducted at Millbanks Penitentiary in England in the 1840’s, the author concludes that although supermax conditions are being used in today’s modern prisons, today’s correctional officials rarely make changes in confinement conditions based on the results of sometimes damaging research. Notes, references