The Generalizability of IR Experiments beyond the United States

Theories of international relations (IR) typically make predictions intended to hold across many countries, yet existing experimental evidence testing their micro-foundations relies overwhelmingly on studies fielded in the United States. We argue that the broad nature of many IR theories makes it especially important to evaluate the extent to which their predictions hold across countries. To examine the generalizability of IR experimental findings beyond the US, we implemented a preregistered and harmonized multisite replication study, fielding four prominent IR experiments across a diverse set of seven democracies: Brazil, Germany, India, Israel, Japan, Nigeria, and the US. We find high levels of generalizability across all four experiments, a pattern further analysis suggests is due to limited treatment effect heterogeneity. Our findings and approach offer important empirical and methodological insights for the design and interpretation of future experimental research in IR.