This paper calculates new measures of human capital. Contrary to the existing literature, they are based on realistic rates of return to education, which are allowed to vary substantially across countries and to some extent over time. The new measures perform well in regression analysis explaining productivity across OECD countries and over time. In OECD samples, coefficient estimates are broadly consistent with the private returns underlying the construction of the new measures of human capital. In a wider sample of countries, most estimates imply additional positive social returns.