Cognitive ability is one of the most basic components for productivity. It alsoplays important roles not only in workplaces but also in various domains overone’s lifetime. In this study, we measure the level of cognitive ability for NorthKorean refugees, which is almost unknown in the literature. Collecting thedata from 300 refugees, we examine the determinants for their cognitiveability, measured by the Raven’s progressive matrices test, and investigate theeffects of cognitive ability on their economic outcomes in South as well asNorth Korea. We find that there is a substantial gap in cognitive abilitybetween North Korean refugees and native-born South Koreans. Aninternational comparison reveals that North Korean refugees’ average cognitiveability is as low as those in other less developed countries. Finally, we findthat cognitive ability is positively correlated with higher social status in NorthKorea as well as economic assimilation after they settle down in South Korea.