Prisonisation is a concept that has permanently entered the conceptual apparatus of prison science, while the phenomenon itself has become the subject of numerous studies by criminologists and penitentiaries. The author of this concept was the American sociologist and prison officer D. Clemmer, the author of the classic monograph “The Prison Community,” the first such comprehensive work that presented the social aspects of prison life. The article presents the essential elements of the concept of prisonisation as a dynamic process during which inmates adapt to the conditions that occur in prison.