This article examines a range of potential causal variables of state legitimacy using a globally representative set of 72 countries accounting for 83 percent of the world’s population. Major theories of legitimacy determinants are advanced and tested using survey and expert data. Three variables (which measure good governance, democratic rights, and welfare gains) are then chosen from among all strongly correlated variables as being the most plausible basis for a causal theory. The theory is then further tested using 31 pairs of countries with similar income levels and in similar regions, which shows a significant positive correlation between performance and legitimacy. The article concludes with suggestions for further research.