The analysis of voting behaviour – and particularly the reasons for the increasing vote share of the National Socialists – in the Weimar Republic and the socio-structural composition of the electorate of the NSDAP are scrutinized by numerous studies. However, a detailed analysis of the results of the Reichstag election on 12 November 1933 is still missing. In this election, the electorate had indeed only the possibility to vote for the NSDAP, but there was a considerable part of spoiled ballot papers that varied significantly over the districts and district-free cities as did the share of non-voters. This article aims at answering the question whether and how indicators for the regional social background can help to explain the different spreading of turnout and void ballots at this so called election. Based on theoretically derived expectations and the election results on the district level, this contribution shows by means of multivariate regression analyses that even if controlling for other factors like the number of inhabitants and the city status, particularly the share of industrial workers and therefore the regional strength of the socialist milieu caused the increased part of invalid votes and non-voters, and not the catholic milieu that was considered to be resilient against National Socialism during the 1920s and early 1930s.