Consistent with recommendations from a U.S. workshop, the World Report on Violence and Health released by the World Health Organization comments on the comparability of data on IPV, focusing on inconsistencies in the way that violence and abuse are defined as a critical element that has thwarted comparability among nations. Two surveys sponsored by the U.S. Government that include information about the magnitude of IPV in the United States are used in this article to illustrate the challenges to be faced in striving for transnational comparability. The two surveys profiled are the National Violence Against Women Survey and the National Crime Victimization Survey. Differences in survey definitions and measures are examined to show how they influence diverse findings. The article then compares survey data with the surveillance data obtained from police or other agency records. This review concludes that it remains to be determined how to establish maximum levels of uniformity and to identify optimal measurement strategies, whether for a single country or across multiple countries. There is not even a consensus about the importance of standardization. Further, it is unclear whether researchers should focus separately on IPV, more broadly on violence and abuse against women as suggested at the U.S. workshop, or even more broadly on gender-based violence as suggested in the report of the Pan American Health Organization. In order to move toward comparable global measures of IPV, mechanisms must be developed for reaching agreement on uniform strategies for minimizing subjectivity and incorporating periodic updates in definitions and methodology. The first steps are to be explicit about the definitions and measures that are being used in research and to continue to explore issues of context that may explain differences in findings. These issues must be discussed and debated with colleagues from other countries in efforts to move toward uniformity in terminology and measurement strategies. 38 references