Many widely used economic models implicitly assume that income shares should be identical across time and space. Although time-series data from industrial countries appear consistent with this notion, cross-section data generally appear to contradict the assumption. A commonly used calculation suggests that labor shares of national income vary from about .05 to about .80 in international cross-section data. This paper suggests that the usual approach underestimates labor income in small firms. Several adjustments for calculating labor shares are identified and compared. They all yield labor shares for most countries in the range of .65.80.

A longstanding question in economics is why some countries are so much richer than others. Today, for example, income per capita in the world's richest countries is roughly thirty-five times greater than it is in the world's poorest countries. Recent work argues that the proximate cause of the disparity is that today's poor countries began the process of industrialization much later and that this process is slow. In this paper we argue that a model of structural transformation provides a useful theory of both why industrialization occurs at different dates, and why it proceeds slowly. A key implication of this model is that growth in agricultural productivity is central to development, a message that also appears prominently in the traditional development literature.