One more from Vox EU. This is by Markus Brückner and Daniel Lederman:
Effects of income inequality on economic growth: ... Conclusion Our empirical analysis is motivated by the theoretical work of Galor and Zeira (1993). who examined the relationship between inequality and aggregate output in the presence of credit market imperfections and indivisibilities in human capital investment. Galor and Zeira’s model predicts heterogeneity in the effects of inequality on aggregate output across countries' initial income levels. Taking this prediction seriously, our econometric model included an interaction between measures of income inequality and countries' initial level of GDP per capita. Instrumental variables estimates showed that income inequality has a significant negative effect on aggregate output for the average country in the sample. However, for poor countries income inequality has a significant positive effect. We document that this heterogeneity is also present when considering investment – in particular, investment in human capital – as a channel through which inequality affects aggregate output. Overall, our empirical results provide support for the hypothesis that income inequality is beneficial to economic growth in poor countries, but that it is detrimental to economic growth in advanced economies.