In the summer of 1941, as the German army advanced through Poland’s eastern borderlands, some Polish, Ukrainian, and Belarusian civilians turned against their Jewish neighbors. Little stood in their way: Soviet control over the Polish territory occupied on September 1, 1939 had broken down, and German control was not yet established. However, notwithstanding the long history of discrimination and violence against Jews in the region and the collapse of state authority, just 9% of ethnically mixed settlements experienced a pogrom that summer.

Why did pogroms against Jews erupt in some localities and not others? This question is at the center of Intimate Violence. The answer, the authors Jeffrey Kopstein and Jason Wittenberg argue, lies in “competing nationalisms” among the ethnically mixed population in the border region (p. 3). The book makes a compelling case that pogroms occurred in localities where the Jewish population had previously fought for political equality and resisted Polish and/or Ukrainian “nation-building projects” (p. 32). According to the authors, supporting “proud and assertive” Jewish politics in interwar Poland meant voting for Zionists who were ready to defend Jewish political and economic rights but remained moderate on social and religious issues (p. 32). The 1941 outbreak of violence against Jews in some localities was thus an attempt by the non-Jewish residents to establish political dominance by eliminating future political competitors. The argument builds on the power-threat theory developed to explain race relations in the postbellum southern United States.

The central hypothesis is supported by quantitative analysis of more than two thousand localities in the Polish borderlands. The authors compiled a wealth of micro-level census and electoral data. Notably, they consider the context of each pogrom to exclude attacks on Jews by the German military. To estimate the voting choices of each ethnic group from aggregated electoral data, the book relies on ecological inference methods. In addition to large-n analysis, Kopstein and Wittenberg leverage qualitative comparisons between the Polish-dominated northeast provinces (Białystok and Polesie) and the Ukrainian-dominated southeast provinces (Volhynia, Lwów, Stanisławów, and Tarnopol).

The book’s empirical analysis indicates that political polarization across ethnic lines is the best predictor of pogrom occurrence, consistent with the power-threat hypothesis. Violence in the summer of 1941 is associated with Jewish support for nationalist parties, the Bloc of National Minorities and the East Galician Zionists. In interpreting this main finding, the authors take care not to blame the victims of pogroms. They attribute Jewish support for nationalist parties to the Polish parties’ failure to include Jews in governing coalitions. Patterns of violence in the Ukrainian-dominated provinces suggest that economic competition also contributed to the violence against Jews. Throughout the book, the authors also consider and eliminate alternative explanations for the occurrence of pogroms, including a long history of anti-Semitism, retribution by the local population against perceived Jewish support for communism, scapegoating of Jews for economic problems, and encouragement by the German occupying forces.

Some empirical limitations remain. First, political support for Zionist parties is not randomly distributed. Thus, the nationalist vote in the 1920s may capture the Jewish response to earlier discrimination and violence, including the 1918–20 wave of pogroms. Relatedly, both political polarization in the 1920s and the 1941 pogroms may share a common cause. Second, the 1921 census data may not adequately capture the composition of the population during the 1941 pogroms due to the bias in recording nationality and Jewish emigration to Palestine in the 1920s and 1930s. The authors acknowledge and compensate for these issues to some extent by deploying alternative indicators, performing a variety of robustness tests, and illustrating the theorized causal mechanisms with qualitative data.

The authors emphasize that “most Poles and civilians of other nationalities were neither perpetrators of . . . nor bystanders to” the 1941 pogroms (p. 130). That “only” one out of ten localities experienced a pogrom is not surprising—pogroms require collective action, and violence took place in the span of merely a few months, during which some Jews fled east, went into hiding, or died at the hands of the Germans. Nevertheless, the authors rightly caution against overstating the extent of violence against Jews on the eve of the Holocaust. Their large-n analysis of pogrom occurrence is a welcome contribution to the largely qualitative research on the Holocaust, and also a sober counterpoint to the heated debate about collaboration between local populations and occupying forces in Eastern Europe during World War II.

The book challenges conventional accounts of ethnic violence and advises against extrapolating from a single case, such as the infamous July 1941 pogrom in the Polish town of Jedwabne (p. 65). The authors are also right to warn against viewing the pogroms exclusively as the product of widespread anti-Semitism (p. 130). At the same time, their thesis that Jews constituted a political threat fails to explain why the 1941 pogroms targeted Jews exclusively. The Ukrainian minority, for one, remained safe even though it outnumbered the Jewish minority, had strong nationalist aspirations, and eventually attacked Poles. The authors’ explanations for why Jews were the first victims—popular anti-Semitism and the German influence—seem somewhat ad hoc (p.112). Not least, pogroms themselves have been used as an indicator of anti-Semitism in the literature.

In the penultimate chapter, Kopstein and Wittenberg briefly discuss the relevance of their argument for understanding anti-Jewish and intercommunal pogroms outside Poland and suggest promising avenues for future research. The book concludes by discussing ways to prevent interethnic violence. The authors contend that cultural assimilation of national minorities does not reduce the likelihood of pogroms. In their view, lowering the nationalist aspirations of ethnic minorities, reducing political polarization, or manipulating group identities to foster interethnic solidarity may be more effective.

By using the power-threat theory to explain the 1941 pogroms, the authors show that theoretical insights from the literature on intergroup conflict in American and comparative politics can help us understand violence during World War II and the Holocaust, a phenomenon still somewhat peripheral to “mainstream” political science. One challenge is that existing applications of the power-threat theory are not limited to periods of state collapse. In the Polish case, the breakdown of state institutions in the summer of 1941 may have untied the hands of the local population, but pogroms against Jews had also occurred in previous periods. Relatedly, political dominance can be achieved by means short of pogroms, including political and economic discrimination; Polish Jews were subject to both well before the summer of 1941.

Overall, Intimate Violence is an original and well-crafted study of interethnic competition on the eve of the Holocaust. The book advances our understanding of the microfoundations of ethnic conflict and challenges existing explanations of violence against Jews in twentieth-century Eastern Europe. Kopstein and Wittenberg also assemble a fine-grained historical data set that could help address further questions about interethnic relations. As such, the book has much to offer scholars of intercommunal violence, nationalism, and Eastern European politics.