Previous studies have reported that nations with extreme inequality in the distribution of income exhibit comparatively high homicide rates. This paper uses data quality ratings in the World Income Inequality Database (WID) to reassess the effect of income inequality on national homicide rates. It estimates both cross-sectional and longitudinal multivariate models with multinational samples and examines the implications of using different data sources of varying quality. It examines whether the previously observed positive effect of income inequality on national homicide rates withstand rigorous controls for the quality of income-distribution data. The analyses reveal that the income inequality/homicide relationship is reasonably robust in cross-sectional analyses. The longitudinal analyses imply that claims for a longitudinal effect of income inequality on homicide rates must be regarded cautiously. Recommendations are presented for future longitudinal studies to include larger samples and high-quality income-distribution data to determine whether the well-established cross-sectional relationship between income inequality and homicide can be generalized to explain changes in national homicide rates. Appendix and references