The article discusses the features of the process of psychological adaptation to a long existence in extreme conditions by prisoners of the Gulag and the National Socialist forced-labor camps in Germany. The Soviet prisoners’ collective biographical experience of survival, reflected in the corpus of ego documents, was analyzed by the author from the standpoint of psychosocial theories created by former prisoners of Theresienstadt, Dachau and Buchenwald, Austrian scientists V. Frankl and B. Bettelheim. The article describes and explores the changes that occurred with the prisoner’s personality at each of the three stages of their psychological perception of the camp realities: primary shock, or traumatization upon entering the camp, apathy, which is viewed as the main defence mechanism of the psyche, and the depersonalization at the time of the release from the camp. The process of adaptation of a prisoner to the camp’s conditions most often involved one or another form of cooperation with the camp administration. The study highlights these types of cooperation, both legal (practice of profession, participation in the camp amateur activities, service in the militarized guard VOKhR, and work as an informant whistle-blower) and illegal (practices of fraternization, scam, bribery and embezzlement, voluntary concubinage of female prisoners with camp personnel). The author classifies belief in God, the ability to value the beauty of nature and enjoy art, engagement in professional activities, self-observation, mental connection with the loved ones, and, equally, the ability to retain a sense of humour as conscious behavioral models that helped prisoners to resist destruction of personality. Along with these behavioral patterns, the study identifies a number of so-called anti-defences that worsened the prisoner’s morale and weakened their personality: immersion in thoughts of their own innocence, which gave rise to an impatient expectation of imminent release, constant dreams of food and home comforts, a tendency to believe camp rumors, aggression. The author also focuses on such issues as the content of the concept of “survival”, limits of the influence of the camp environment on a person, transformation of the identity of a surviving prisoner.