After spending three days in Vienna, Bettelheim is transferred to Dachau concentration camp for four months and then to Buchenwald. His wife goes to the United States. Later Bettelheim deposes in a document signed L-73, saying that he was able to survive partly because he could understand the mental processes of the SS guards and officers.

I worked in at least 20 different labor groups whose number varied from 20 or 30 all the way up to a few hundreds. I slept in five different barracks, in each of which 200 or 300 prisoners lived. In this way I came to know personally at least 600 prisoners at Dachau (out of approximately 6,000) and at least 900 at Buchenwald (out of approximately 8,000). Although older prisoners of the same category lived together in barracks, all categories were mixed at work so that I was able to contact and interview prisoners of all types. The main different categories were : political prisoners; “work-shy” prisoners, that is, persons who did not agree to work wherever the government wanted them to work, or who had changed working places to get higher wages, etc.; former members of the French Foreign Legion and spies; Jehovah’s Witnesses and other conscientious objectors; Jews; criminals; and other groups, e.g. former members of such suppressed Nazi groups as the followers of Roehm who were still alive. I was thus afforded an opportunity of interviewing all different groups and in this way secured an adequate sampling. was able to find only two other persons whose intelligence and training qualified them to participate in my investigation. These individuals spoke to several hundred prisoners. Every day during the morning count of the prisoners, while waiting for assignment to labor groups, reports were exchanged, and theories discussed. These talks proved very helpful in clarifying mistakes due to taking a one-sided viewpoint.

Influential friends in America ask the State Department to pressure the German authorities for his release and he is set free in April 1939.