In the penitentiary setting, inmates are deprived of liberty, of goods and services enjoyed on the outside, of heterosexual relationships, of autonomy, and of personal safety. In this situation inmates tend to adopt primitive social behavior and to regress to a violent stage within a prison society guided by violent norms. There are four principles of operation for the prison society: 1) the principle of violence, which is the fundamental factor in interpersonal relationships of dominance and subordination; 2) the principle of exploitation, which enables prisoners 'higher' in the prison hierarchy to use 'lower' prisoners to their own ends; 3) the principle of social solidarity, which unites prisoners against guards, and 4) the principle of status quo, which is maintained by both prisoners and guards to avoid disturbance of a delicate equilibrium. Part of the imprisonment syndrome is the development of hostility and irreverence toward authority. Adaptation to imprisonment actually means only that the prisoner has been assimilated into the prison society and has subordinated himself to the subculture's principles. The attitudes acquired remain in varying degrees after release and thus consitute a factor conducive to crime. Notes are supplied. --in French.