Results indicated that the rising strength of leftist political parties associated with Jews in pre-World War II Germany ignited anti-Semitic violence. The findings challenge previous research linking minority group size and economic conditions to levels of intergroup violence. However, the authors are careful to point out that they do not dispute the general theoretical claim that larger minority group size and deteriorating economic conditions can increase the likelihood of intergroup violence. The model of intergroup violence presented here, referred to as the political threat model, can be used to understand intergroup violence at times and places where population size changes very little but political power is contested and ideologically polarized. The development of the political threat model was based on the perspective that intergroup violence is partly reactionary and used as a means of informal social control. Research methodology involved a review of the volumes contained in the “American Jewish Year Book” (AJYB), which has been published annually since 1899. This publication includes information about laws that concern Jewish affairs and accounts of discrimination or violence against Jews. The analysis focused on all violent incidents involving Jewish victims, economic conditions, Jewish population size, the presence of an election, Hitler’s period of control in Germany, and leftist party electoral success, which was measured using the percentage of all votes cast for leftist parties in Germany. Data were analyzed using a negative binomial model as well as a Durbin-Watson test for serial correlation. Future research using the political threat model is suggested, including an investigation of whether environmental terrorism would increase in areas where environmental protection laws were rescinded. Tables, figures, footnotes, references