The demise of the Weimar Republic is often at least partially attributed to extreme polarisation as well as aggressive and antagonistic political competition amongst political parties. How were these processes reflected in the electoral communication of parties at the time? Did the civility of electoral communication (the ‘how’) and the communicated policy stances (the ‘what’) change over time in response to economic context conditions or the entry of new challenger parties with more extreme positions? This study explores the development of electoral communication of German political parties between 1920 and 1932. Based on a new corpus of the official election appeals of parties and the relational coding of the content of these documents, it provides the first systematic mapping of the campaign strategies and the policy positions of parties over time. The results of the study do not only provide insights about political processes that played a part in the downfall of the first German democracy, but also important lessons for the role of political competition in bolstering or undermining democratic resilience in the current era of increased polarisation.