Tables provide the following high-level security information for each prison system: definition of "high-level security," criteria for placing an inmate in high-level security, distinction between high-risk and high-level security, status review for possible removal from high-level security, status consideration, housing features, locking procedures, unlocking procedures, cell restrictions, movement, facility transfers, visitation, reading material, exercise, telephone use, writing material, program participation, and work detail. Although the survey found no single definition of "high-level security" inmates among the prison systems surveyed, for the most part the high-level security designation is given to inmates who are escape risks, child molesters, and terrorists; it is also used for those who have committed disciplinary infractions, who require protective custody, who are considered sexual predators, and who are sentenced to death. A total of 23 of the U.S. systems indicated there is basically no difference between high-risk and high-level security inmates. The average percentage of the prison population designated as high-level security was found to be 11.35 percent for the U.S. systems. Established review procedures for changing security designations are in place in all of the systems. For the most part, high-level security inmates are restricted to their cells at all times, with the exception of the limited hours scheduled for showering and exercise. Time out of cells is permitted for approved programs and activities in 12 of the U.S. systems. 4 tables