Intergenerational mobility—the association between parents’ and adult children’s economic wellbeing—is an important sociological concept because it provides information about inequality of opportunity in society, and it has gained relevance in the recent past due to the increase economic inequality in most of the affluent world. This article provides an overview of the different measures of mobility used by sociologists and economists, as well as main empirical findings about mobility. I then move to topics that push mobility analysis beyond its bivariate focus: The association between intergenerational mobility and economic inequality, the mechanisms for mobility, and the validity of mobility as a measure of inequality of opportunity. I suggest that the association between mobility and inequality is likely spurious, driven by varying institutional arrangements across countries, and that mobility analysis is most useful when focused on describing the bivariate intergenerational association across countries and over time.

The notion of “economic development” dominates aid policy. A nation’s per capita Gross Domestic Product (gdp) determines whether that country is considered developed or less developed, and the standard measure of any developmental progress is gdp growth. This article investigates the evolution of the concept of economic development, as it emerged from a specific combination of modeling, statistics and political circumstances. In this story, Arthur Lewis played a decisive role, but only by building upon Colin Clark’s first global national income statistics, an indispensible foundation for Lewis’s seminal model of economic development. This model was embraced by policy makers longing for a theoretical framework to clarify and operationalize the hitherto vague concept of development. More importantly, however, the statistical indicator on which Lewis based his theory had already been universally accepted. In other words: statistics came before theory. This holds important lessons for alternative development ideas. It explains why the idea of economic development remains so firmly entrenched and suggests the conditions that might be necessary for an alternative theory to take hold.