The German Neurological Society (DGN) instigated an investigation into potential incrimination of some of the previous leading members regarding their Nazi involvement. The persons in question include former (honorary) presidents and honorary members of the DGN (or the predecessor organizations) and the name givers of prizes awarded by the DGN. This introduction to the following biographies explains the difficulties and the broad discretionary leeway needed to establish an involvement in Nazi activities going beyond justiciable crimes against humanity on the basis of formal criteria (e.g. membership in the NSDAP and/or other NS organizations, involvement in Nazi crimes) and/or substantive indications (e.g. statements advocating the NS ideology, personal contacts to Nazi functionaries, active support of the system). A longitudinal analysis from 1945 until the present day reveals time-related variations in assessing who and why someone was considered to be a Nazi. A current overview of historical projects initiated by medical societies in Germany demonstrates that the endeavor of the DGN to deal with its Nazi involvement will be an integral part of the interdisciplinary "culture to cope with the past" of medical associations. Finally, it should be borne in mind that the fabric of history consists of a different material than clinical medicine or its natural scientific foundations. Checklists or scores for measuring NS involvement thus cannot and will not exist. Instead, balanced historical interpretations are needed as attempted by the biographical reconstructions presented in this volume.