The study describes and analyzes the uses and abuses of solitary confinement as a mechanism of social control in prison. It examines the deterrent and labeling effects of experiences with the 'prison's prison' and the personal and criminalistic attributes of the 706 inmates. The study encompasses a decade replete with turmoil in the prison (1966-75). It found that the deterrent effect of segregation in the modal number of trips to segregation was minimal and that the amount of time spent in segregation did not substantially increase with increased number of previous infractions. The possibility exists that, except for social defense considerations, segregation should be used only for inmate violators who have been convicted of serious infractions for the third and succeeding times. Data tables, notes, footnotes, and 19 references are supplied.