The Security Housing Unit (SHU) confines more than 1,000 prisoners for periods of 6 months to several years. It has a monotonous and harsh design that is devoid of social stimulation. The housing units have no windows, and inmates are not allowed to see grass, trees, or shrubbery. Bare concrete walls form an exercise yard in which inmates engage in solitary recreation, with no equipment, for approximately 1.5 hours per day in good weather. Prisoners who can afford them can have radios and small televisions in their cells, but they have no other regular activities and are fed in their cells on tray slots in the cell doors. They do no work and have no opportunities for educational or vocational training. They are denied contact visits of any kind. As a result, some inmates begin to lose the ability to set limits for themselves, while others lose the ability to initiate behavior of any kind. Some become socially withdrawn. Some express their frustration through violence. Many become suicidal or self-mutilating. This environment can be psychologically destructive for anyone who enters and endures it for significant periods of time, particularly those with preexisting psychiatric disorders. Inmates risk profound and chronic alienation and asociality. Reference notes