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 U.S. 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 U.S., we implemented a pre-registered and harmonized multi-site replication study, fielding four prominent IR experiments across a diverse set of seven democracies: Brazil, Germany, India, Israel, Japan, Nigeria, and the U.S. 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. APSR Data Editors' Note: APSR Data Editors have reviewed included documentation for completeness and have successfully reproduced all figures and tables in the article using the code and data included in this deposit. Data editors do not review results presented in appendices or supplementary materials.