Do cultural attitudes affect institutions and economic performance? This paper suggests they do. To measure the impact of cultural attitudes we use prevalence rates of the common parasite Toxoplasma gondii which is known to affect individual attitudes and societal values in predictable ways. By using prevalence rates of Toxoplasma as instrument for cultural variation, we are able to isolate the effects of cultural attitudes on institutions, distinguishing them from effects of institutions and economic outcomes on culture. We find that our indicators of cultural attitudes are significant determinants of institutional quality, and strong predictors of long-run economic performance.