Aggregate indexes of the quality of governance, covering large samples of countries, have become popular in comparative political analysis. Few studies examine the validity or reliability of these indexes. To partially fill this gap, this study uses factor, confirmatory factor and path analysis to test both measurement and causal models of the six Worldwide Governance indicators. They purportedly measure distinct concepts of control of corruption, rule of law, government effectiveness, rule quality, political stability, and voice and accountability. Rather than distinguishing among aspects of the quality of governance, we find that they appear to be measuring the same broad concept.