Previous work shows that higher levels of education quality (as measured by international student achievement tests) increase growth rates of national income. This paper begins by confirming those findings in an analysis involving more countries over more time with additional controls. We then use the panel structure of our data to assess whether the mechanism by which education quality appears to improve per capita income levels is through shifting the level of the production function (probably not), through increasing the impact of an additional year of education (probably not), or through increasing a country’s rate of technological progress (very likely). Mortality rates complement income levels as indicators of national well-being, and we extend our panel models to show that improved education quality increases the rate of decline in infant mortality. In the analysis of growth, we find a stronger impact of education quality and of years of schooling in open than in closed economies.