What caused individual Germans to vote for or join the Nazi party in the 1930s is still not fully understood, in part because current research relies on either aggregate quantitative or small-scale qualitative data. We collect individual-level longitudinal data from over 10,000 denazification questionnaires (Fragebogen), which were widely distributed in Germany’s US occupation zone between 1945 and 1949, containing detailed information about respondents’ past membership in Nazi organizations, retrospective vote choices in 1932-33, their education, occupation and income histories, and other socio-demographics. An initial descriptive analysis sheds light on whether certain social or occupation groups – such as young, uneducated men or Catholics – were more or less likely to be (early) supporters of the Nazi regime. We further present evidence from different analyses testing the sincerity of responses in the questionnaires. Our findings contribute to the understanding of demographic characteristics and potential motivations of individuals who vote for and participate in populist radical right-wing movements.