This paper offers new evidence on the sources of cross-country income differences. It exploits the idea that observing immigrant workers from different countries in the same labor market provides an opportunity to estimate their human-capital endowments. These estimates suggest that human and physical capital account for only a fraction of cross-country income differences. For countries below 40 percent of U.S. output per worker, less than half of the output gap relative to the United States is attributed to human and physical capital.

We reconsider the role for human capital in accounting for cross-country income differences. Our contribution is to bring to bear new data on the pre- and post- migration labor market experiences of immigrants to the U.S. Immigrants from poor countries experience wage gains that are only 40 percent of the GDP per worker gap, which implies that "country" accounts for 40 percent of income differences, while human capital accounts for 60 percent. Our approach handles selection by comparing the wage of the same individual in two different countries. We also provide evidence on and a correction for skill transfer.